Small Drinking Water Systems Handbook

Transcription

Small Drinking Water Systems
Handbook
A Guide to “Packaged”
Filtration and Disinfection
Technologies
with
Remote Monitoring and
Control Tools
A “Packaged” Solution For A Site In Rural West Virginia
Filtration (Before)
Ultrafiltration System
(After)
Remote Monitoring
and Control
DISCLAIMER
The information presented in this document relates to research
on small drinking water systems conducted by the Water Supply and Water Resources Division (WSWRD) of the United
States Environmental Protection Agency (EPA). The
WSWRD is a division of the National Risk Management
Research Laboratory, Office of Research & Development.
This research was performed at the EPA’s Test & Evaluation
Facility in Cincinnati, Ohio, and at other field locations. It
has been subjected to the EPA’s peer and administrative review. Mention of trade names or commercial products in this
document does not constitute an endorsement or recommen
dation for use.
EPA/600/R-03/041
May 2003
Small Drinking Water Systems
Handbook
A Guide to “Packaged” Filtration and
Disinfection Technologies with Remote
Monitoring and Control Tools
U.S. Environmental Protection Agency
Office of Research and Development
National Risk M anagem ent Rese arch Lab oratory
Water Supply and Water Resources Division
Contents
Page
List of Tables __________________________________________________________ ii
List of Figures ________________________________________________________ iii
Acronyms and Abbreviations___________________________________________ iv
1.0
Introduction ____________________________________________________ 1
2.0
Contaminants in Drinking Water __________________________________ 3
3.0
Common Water Supply Problems and Recommended Solutions _____ 5
4.0
Regulatory Overview ____________________________________________ 9
5.0
Common Violations ____________________________________________
13
6.0
Treatment Technologies _________________________________________
15
7.0
Point-of-Use/Point-of-Entry Applications __________________________
35
8.0
Remote Monitoring/Control _____________________________________
41
9.0
A Real World Packaged Solution _________________________________
45
10.0
Funding and Technical Resources ________________________________
49
11.0
Additional Information Sources __________________________________
55
12.0
References ____________________________________________________
63
i
List of Tables
Table 3-1
Table 3-2
Table 4-1
Table 4-2
Table 4-3
Table 4-4
Table 4-5
Table 5-1
Table 5-2
Table 6-1
Table 6-2
Table 6-3
Table 6-4
Table 6-5
Table 6-6
Table 6-7
Table 6-8
Table 6-9
Table 6-10
Table 7-1
Table 7-2
Table 8-1
Table 8-2
Table 9-1
Table 10-1
Table 10-2
Table 10-3
ii
Page
Troubleshooting/Testing for Common Water Supply Problems __________ 5
Emergency Disinfection Treatment for Drinking Water __________________ 6
Size Categories of Public Water Systems _____________________________ 10
Distribution of Water Systems ______________________________________ 10
National Level Affordability Criteria __________________________________ 11
General Sample Monitoring Schedule for Small Systems ______________ 11
Small System Regulatory Summary _________________________________ 12
Total Coliform Bacteria Violations for the Period October 1, 1992 through
December 31, 1994 ________________________________________________ 13
Chemical Contamination Violations for the Period October 1, 1992
Through December 31, 1994________________________________________ 13
Surface Water Treatment Compliance Technology _____________________ 16
Regulated Contaminant List (partial) and Possible Removal Technologies 17
Bag Filter Characteristics ___________________________________________ 20
Bag Filtration Performance Summary ________________________________ 22
Cartridge Filter Characteristics ______________________________________ 24
Cartridge Filtration Performance Summary ___________________________ 25
Membrane Filtration Performance Summary _________________________ 25
Filtration Summary Table ___________________________________________ 26
Summary of Disinfectant Characteristics Relating to Biocidal Efficiency __ 29
Disinfection Summary Table ________________________________________ 33
Key Feature Summary of Commonly used POU/POE Technologies _____ 37
Summary of Treatment Technologies and Costs ______________________ 38
Amenability of RTS to Treatment Technologies Used for Small Water
Systems __________________________________________________________ 42
Cost Estimates of SCADA System Components _______________________ 42
Raw Water Quality and Contaminant Specifications ___________________ 45
Federal Funding Programs for Small Public Water Systems ____________ 52
Technical and Administrative Support for Small Public Water Systems __ 52
Foundation Backing Rural Economic Development Program ___________ 53
List of Figures
Page
Figure 1-1
EPA Test & Evaluation Facility, Cincinnati, OH _________________________ 1
Figure 3-1
Canteen and Tablets for Emergency Purification Using Iodine __________ 7
Figure 6-1
Particle Size Distribution of Common Contaminants and Associated
Filtration Technology _____________________________________________ 18
Figure 6-2
Clogged Prefilter _________________________________________________ 19
Figure 6-3
Typical Bag Filter _________________________________________________ 20
Figure 6-4
Cut-Away of Bag Filter ____________________________________________ 21
Figure 6-5
Bag Filter Showing Rip in Seam ___________________________________ 21
Figure 6-6
Bag Filter Showing Bag Rupture ___________________________________ 21
Figure 6-7
Bag Filters Showing Discoloration Associated with Bypass ___________ 21
Figure 6-8
Bag Filters Showing Discoloration Associated with Bypass ___________ 21
Figure 6-9
Different Configurations of Bag Filters Tested _______________________ 21
Figure 6-10 Influent vs Effluent Particle Counts _________________________________ 22
Figure 6-11 New Bag ________________________________________________________ 22
Figure 6-12 Dirty Bag ________________________________________________________ 23
Figure 6-13 Cartridge Filters and Housings ____________________________________ 23
Figure 6-14 Dirty and Clean Cartridge Filters ___________________________________ 24
Figure 6-15 Normal Cartridge Filter ___________________________________________ 24
Figure 6-16 Collapsed Cartridge Filter _________________________________________ 24
Figure 6-17 UF System ______________________________________________________ 26
Figure 6-18 Cracked Plastic Adaptor Used Between Membranes _________________ 26
Figure 6-19 Log Removal of Beads vs. Membrane Run-Time _____________________ 27
Figure 6-20 Number of Beads in Effluent vs. Run Time __________________________ 27
Figure 6-21a Cryptosporidium Oocyst on Upper Surface of 3 Micron Pore _________ 27
Figure 6-21b Cryptosporidium Oocyst Coming through 3 Micron Pore _____________ 27
Figure 6-22 Micro Filtration System ___________________________________________ 27
Figure 6-23 On-Site Chlorine Generator #1 ____________________________________ 32
Figure 6-26 Package AOP Plant MTBE Removal vs Time, 30 µg/L Batch Test Run ___ 34
Figure 6-27 Package AOP Plant Formation of t-BF vs Time Injecting 30 µg/L MTBE _ 34
Figure 7-1
Typical RO Unit under a Kitchen Sink _______________________________ 36
Figure 7-2
AOP POE Unit Installed in a Cellar __________________________________ 40
Figure 8-1
Possible Layout(s) of a Remote Telemetry System ___________________ 43
Figure 9-1
McDowell County ________________________________________________ 45
Figure 9-2
Old Treatment System ____________________________________________ 45
Figure 9-3
Packaged UF System _____________________________________________ 46
Figure 9-4
New Cinder Block Building ________________________________________ 46
Figure 9-5
Welcome Screen _________________________________________________ 47
Figure 9-6
System Summary ________________________________________________ 47
iii
Acronyms and Abbreviations
AOP
ARC
BAT
bdl
CCL
cfu
cm2
CT
CTA
CWS
DC
D/DBP
DWS
DWSRF
EPA
ESWTR
ETV
GAC
gpd
gpm
HAA
HFTF
hh
HPC
HUD
IHS
IRS
MCL
MCLG
MF
MHI
µg/L
MCPSD
mg/L
mL
mm
M/R
MTBE
MWCO
mWsec
NCWS
nd
NF
iv
advanced oxidation process
Appalachian Regional Commission
best available technology
below detection limit
Contaminant Candidate List
colony-forming unit
square centimeter
contact time
cellulose triacetate
community water systems
direct current
disinfectants/disinfection by-products
drinking water systems
Drinking Water State Revolving Fund
United States Environmental
Protection Agency
Enhanced Surface Water Treatment
Rule
Environmental Technology Verification
granular activated carbon
gallons per day
gallons per minute
haloacetic acid
high-flow, thin film
household
heterotrophic plate count
Housing and Urban Development
Indian Health Service
Internal Revenue Service
maximum contaminant level
maximum contaminant level goal
microfiltration
median household income
micrograms per liter
McDowell County Public Services
Division
milligrams per liter
milliliter
millimeter
monitoring/reporting
methyl-tert-butyl-ether
molecular weight cut-off
milliwatt second
non-community water system
not detected
nanofiltration
nm
NPDWR
nanometer
National Primary Drinking Water
Regulations
NTNCWS non-transient non-community water
system
NTU
nephelometric turbidity unit
O&M
operation and maintenance
O3
ozone or ozonation
PCE
perchloroethylene
PAH
polynuclear aromatic hydrocarbon
PDCO
pore diameter cut off
PLC
programmable logic controller
POE
point of entry
POU
point of use
ppb
parts per billion
psi
pounds per square inch
PVC
polyvinyl chloride
PWS
public water system
REA
Rural Electrification Administration
RO
reverse osmosis
RTS
remote telemetry systems
RUS
Rural Utilities Service
SCADA Supervisory Control and Data
Acquisition
SOC
synthetic organic compound
SDWA
Safe Drinking Water Act
SDWR
Secondary Drinking Water Regulations
SMCL
secondary maximum contaminant level
SWTR
Surface Water Treatment Rule
T&E
Test and Evaluation
TBA
t-butyl alcohol
TFB
t-butyl formate
TCDD
tetrachlorodibenzo-p-dioxin
TCE
trichloroethylene
TDS
total dissolved solids
THM
trihalomethane
TNCWS Transient non-community water system
TOC
total organic carbon
TT
treatment technology
UF
ultrafiltration
UV
ultraviolet
UV/O3
ultraviolet/ozone or ozonation
VOC
volatile organic compound
WSWRD Water Supply and Water Resources
Division
1.0 Introduction
Those of you who live in small communities, enjoy
camping, eating in restaurants, or work at a location
that provides its own drinking water, are entitled to
the safest and most economical supply of water. The
federal government recognizes that safe and affordable drinking water is something that all are entitled
to and not just those who live in “big” cities. However, with this recognition comes responsibility.
Current and future drinking water regulations apply
to all drinking water systems that serve at least 25
consumers or 15 connections for at least 60 days per
year. These federal and state regulations are designed
and implemented to manage, protect and enhance the
quality of drinking water provided to all consumers.
To Find Reports on Several Small System Issues:
www.epa.gov/safewater/smallsys/ssinfo.html
These regulatory requirements pose a “serious”
challenge to the small, public water system (PWS)
operators (serving fewer than 10,000 people) that
often do not have the technical, managerial, or
financial resources to adequately meet these require
ments. Also, there are several different approaches to
treating, distributing, and maintaining drinking water
quality to meet the same regulatory requirements.
Selecting an appropriate approach requires a basic
knowledge and understanding of types of contamina
tion, available treatment technologies, distribution
system fundamentals, and applicable regulations.
Appropriate technology should be selected based
upon an understanding of these elements combined
with site-specific criteria, such as source water
location, availability of funding, vendor support, and
ease-of-operation.
(T&E) Facility (Figure 1-1) in Cincinnati, Ohio, and
at other field locations. The WSWRD is a division of
the National Risk Management Research Laboratory,
Office of Research & Development.
Thus, the objective of this handbook is to provide
information to the small system operator, manager,
and/or owner (you might be all of these) about
different approaches to providing safe and affordable
drinking water to your community.
This handbook includes the following information:
■
Common types of contaminants found in drinking
water;
■
Common water supply problems and
recommended solutions;
■
Applicable regulations, monitoring and reporting;
■
Common regulatory violations;
■
Treatment technologies most likely to work on a
variety of contaminants;
■
Specific information about innovative filtration
and disinfection technologies;
■
Information on Point-of-Use/Point-of-Entry
systems;
■
Information regarding remote monitoring and
control of systems from off-site locations (as well
as filing state compliance reports on time);
■
Real-world “lessons learned”;
■
Information about funding and technical resources
to implement suitable technologies that meet
applicable regulations; and
■
Sources of additional information.
Considerable information about small drinking
water systems is already available, much of it
from the United States Environmental Protec
tion Agency (EPA). The intent of this
handbook is to highlight information
appropriate to small systems with an empha
sis on filtration and disinfection technologies
and how they can be “packaged” with remote
monitoring and control technologies to provide
a healthy and affordable solution for small
systems. EPA evaluated several commercially
available pre-fabricated “package plants”
suitable for small systems. This document
provides a background on regulations perti
nent to small systems and presents a sum
mary of related research conducted by EPA’s
Water Supply and Water Resources Division
(WSWRD) at the EPA Test & Evaluation
Figure 1-1. EPA Test & Evaluation Facility, Cincinnati, OH.
1
2
2.0 Contaminants in Drinking Water
Water is the universal solvent, and most materials
will eventually dissolve in it. Water found in nature
generally contains a variety of contaminants such as
minerals, salts, heavy metals, organic compounds
(compounds that contain carbon and can occur
naturally or be man made, such as gasoline, dry
cleaning solvents, or pesticides); radioactive residues;
and living (microbiological) materials, such as
parasites, fungi, and bacteria. These materials enter
water through natural processes, such as contact with
rocks, soil, decaying plant and animal matter, and
other materials. Human and animal wastes are the
primary contributors to microbiological contamina
tion of water. Industrial and agricultural sources can
also introduce chemical, pesticide, and herbicide
residues into water. [1]
Federal and/or state regulations are designed to
implement the following four basic strategies to
safeguard the quality of our drinking water:
■
Source Protection – Regulations are
designed to prevent the contamination of
source water, such as lakes, rivers and water
wells that PWSs use. The government
regulates land-use and the constructionlocation(s) of water treatment facilities to
control potential source(s) of pollution from
contaminating source water.
■
Maximum Contaminant Levels (MCLs)
and Maximum Contaminant Level Goals
(MCLGs) – The MCLs are the highest level
of a particular contaminant that is allowed in
drinking water. MCLGs are the highest level
of a contaminant in drinking water below
which there is no known or expected risk to
health. MCLs are Federally enforceable
standards, while MCLGs are non-enforceable
guidance.
■
Treatment Technology (TT) – Most PWSs
use some form of TT, so that the water will
be palatable and safe to drink. Many systems
(but not all) require routine disinfection as a
safeguard against bacterial or viral
contamination.
■
Monitoring/Reporting (M/R) – M/R is
critical for ensuring compliance with the
various regulatory requirements. Monitoring
and reporting is essential in letting you know
whether your system is working properly and
protecting your customers. Regulations
typically require PWSs to routinely sample
treated (or finished) water, and submit the
samples to the state or local agencies. The
submitted samples are tested for a broad
range of potential contaminants. If
unacceptable levels of contaminants are
found, the water supply owner or operator is
legally responsible for informing the people
who use the water, and taking steps to
eliminate potential health hazards. The
frequency of M/R activity varies depending
upon location and system size.
When most people see or hear the word “contami
nated,” it signals danger or disease. However, EPA
defines a contaminant as “any physical, chemical,
biological, or radiological substance or matter in
water.” Whether water is safe to drink depends on the
specific contaminants it contains, how much of each
contaminant is present, and how these contaminants
affect human health.
For example, cloudy or slightly off-color water
sometimes may not be dangerous to drink, while
water that is perfectly clear may contain tasteless,
odorless, and colorless contaminants that cause
serious health effects. Similarly, some substances in
small concentrations, such as iron, are good for
human health. Others, such as fluoride, may be
beneficial at low levels and cause health problems at
higher levels.
Therefore, the PWS source(s) must be protected from
harmful levels of contamination. The PWSs typically
treat the raw source water by filtration and disinfec
tion. Disinfection is usually achieved by applying
chlorine or commercial bleaches. Combined filtra
tion/disinfection treatment is usually sufficient to
remove visible contaminants and kill most bacteria/
viruses. However, too little filtration and disinfection
can result in a higher risk of a wide variety of
stomach and intestinal illnesses. Too much disinfec
tant with too little filtration can result in the forma
tion of disinfection byproducts (for example,
trihalomethanes) and a higher risk of cancer. Therefore, it is important to have technologies in place to
monitor and enhance the treatment system operation,
thereby improving the overall water quality provided
to consumers.
[2]
3
4
3.0 Common Water Supply Problems
and Recommended Solutions
It is important to be able to identify common water
supply problems because testing for every possible
harmful contaminant (petroleum products, pesticides,
heavy metals, bacteria, nitrate, volatile organic
compounds, radioactive substances, etc.) is very
expensive. Therefore, it is important to be able to
identify the potential contaminant and request a
specific laboratory test. Table 3-1 provides general
guidance on conditions that may prompt you to have
your water tested. Generally speaking, if your water
changes taste, odor, or color suddenly, you may want
to contact the local health department, state, or EPAs
regional office for advice before you begin paying for
any tests.
Test samples should always be sent to a certified
laboratory. The laboratory provides the test results in
a report format that typically indicates the amount of
a specific contaminant in your water sample exFor a List of Links to Certified Laboratories:
www.epa.gov/safewater/faq/sco.html
pressed as a concentration, i.e., a specific weight of
the substance in a specific volume of water (e.g.,
milligrams/liter or mg/l). The test results also may
use other symbols and abbreviations. The laboratory
may also report the finding as “bdl” (below detection
limit) or “nd” (not detected) or a numerical result
using the symbol for “less than” (<). For example, if
your report lists a result of <0.03 mg/l for arsenic,
this means that 0.03 mg/l [milligrams per liter] is the
detection limit of the test for arsenic, and the water
had less than 0.03 mg/l arsenic in it, if at all.
The test result provided by the laboratory
should then be compared to the federal standards
(MCLs, MCLGs, etc.) and to other guidance num
bers, such as health advisories, to assess the potential
for health problems. Health advisories specify levels
of contaminants that are acceptable for drinking
water over various lengths of time: one-day, ten-day,
longer-term (approximately seven years), and lifetime
exposures (essentially the same as MCLGs). These
standards are not legally enforceable, and typically
the numbers change as new information becomes
Table 3-1. Troubleshooting/Testing for Common Water Supply Problems [1]
Conditions or nearby activities
Recommended test
Recurrent gastrointestinal illness
Coliform
Distribution system and/or household plumbing contains
lead
pH, alkalinity, hardness, lead, copper
Radon in indoor air or region
Radon
Scaly residues and/or soaps do not lather
Hardness
Stained plumbing fixtures, laundry
Iron, copper, manganese
Objectionable taste or smell (such as rotten egg odor)
Hydrogen sulfide, lead, copper, cadmium, pH, alkalinity,
hardness, metals
Water is cloudy, frothy, or colored
Color, detergents
Corrosion of pipes, plumbing
pH, lead, copper, cadmium, alkalinity
Rapid wear of water treatment equipment
pH, lead, copper, cadmium, alkalinity, hardness
Nearby areas of intensive agriculture
Nitrate, pesticides, coliform bacteria
Nearby coal, other mining operation
Metals, pH, lead, copper, cadmium
Gas drilling operation nearby
Chloride, sodium, barium, strontium
Gasoline or fuel oil odor
Volatile organic compounds (VOCs)
Nearby industrial activities
VOCs, synthetic organic compounds (SOCs)
Dump, landfill, factory or dry-cleaning operation nearby
VOCs, pH, sulfate, chloride, metals
Salty taste and seawater, or a heavily salted roadway
nearby
Chloride, Total Dissolved Solids (TDS), sodium
5
available. However, if MCLs are not being met and
the treatment system is working optimally, alternative
treatment technologies should be explored. Section
6.0 provides a brief overview of treatment technolo
gies and their suitability to treat certain type(s) of
contaminants.
Emergency water purification
Microbiological contamination of a PWS may come
from the failure of a disinfection system, a cross
connection (a wastewater pipe gets connected to a
water pipe), a breach/break in the piping system
(which allows non-treated water into the piping), or a
contaminated source (as in a well). In the event of an
emergency, or due to a general concern over the
potential contamination of a drinking water source,
simple measures can be taken to disinfect sufficient
quantities of water to satisfy basic household needs
until the crisis is resolved. PWS Operators should
notify their customers about drinking water emer
gency situations in the manner specified by their local
or state agency. The operator should also advise their
customers of emergency water purification methods
under such circumstances. Emergency water purifi
cation methods include heat and chemical treatment.
Heat Treatment
1. Strain water through a clean cloth into a clean
pot to remove any sediment and/or floating
debris.
2. Heat and bring to a rolling boil for 1 full minute
or more. Allow the water to cool, and transfer it
to a clean covered container. Refrigerate if
possible. (Remember, at higher elevations, water
boils at lower temperatures and boiling may not
treat parasites or bacteria. Under such scenarios,
chemicals or pressure cookers should be used.) [3]
Chemical Treatment*
Several chemical treatment alternatives are available
for emergency water disinfection. See Table 3-2 for a
summary of these methods. Chlorine, in various
forms, is used for chemical disinfection. [3] The
other popular disinfection method uses iodine, such
as, the tincture of iodine and tetraglycine
hydroperiodide (iodine) tablets. In case of using a
manufacturer supplied tablets, the manufacturer’s
instructions should be followed carefully. This type
of purification is intended for short-term use only.
Remember to keep all disinfectants out of the reach
of children or anyone that may not understand the use
of these chemicals.
Also, the data in Table 3-2 indicate the quantity of the
product(s) required to release 10 mg of chlorine or
iodine per liter of water. Recommended contact time
6
Table 3-2. Emergency Disinfection Treatment for
Drinking Water (10-mg/liter dose, 30-min.
contact time) [4]
Available
Disinfectant
(%)
Disinfectant
Quantity
Gallons
Treated
70
1 tablet
80
Iodine or
chlorine
tablets
1.0-1.6
2 tablets
0.25
Laundry
bleach
5.3
1
tablespoon
20
2
1
tablespoon
8
Commercial
Product
Hypochloride
pellets
Tincture of
iodine
is at least 30 minutes to ensure maximum disinfec
tion. The following is a recommended method for
disinfection using chlorine or iodine tablets.
1. Using chlorine tablets: Strain the water and fill a
gallon-sized milk jug to approximately ¾ full.
Add six (6) drops of chlorine (household bleach)
if the water is clear, or twice that amount if the
water is cloudy. Shake vigorously and allow it
to stand for 30 minutes. A slight odor of
chlorine should be present. Poorly strained
water (i.e., water with debris) or water that is
contaminated with very small particles or
bacteria (and may be cloudy or clear) will use
more chlorine. Therefore, it is very important to
use the proper amount of chlorine. A basic pool
grade chlorine test kit can be used to measure
residual chlorine or simply smell the water. If
there is no scent of chlorine, then repeat the
dosage and let the water stand for an additional
15 minutes.
2. Using tetraglycine hydroperiodide (iodine)
tablets, and iodine taste and odor neutralizing
(ascorbic acid) tablets: Strain the water and fill a
quart or liter container (canteen). Figure 3-1
shows a picture of a canteen. Add two (2) iodine
tablets to the container. Cap the container
loosely to allow a small amount of leakage.
Wait five (5) minutes (the tablets will dissolve
but note that the tablets do not have to
completely dissolve to be effective) and shake
the container to allow the screw threads to
moisten, then tighten the cap. Wait for thirty (30)
minutes before drinking the water. If after 30
minutes the taste and odor of the iodine is a
problem, then use two (2) tablets of ascorbic
acid per liter of water to neutralize the iodine.
Never add the iodine and the ascorbic acid at the
same time, this will stop the disinfection.
Neutralizing
Tablets
Iodine
Tablets
Figure 3-1. Canteen and tablets for emergency purification
using iodine.
3.
Keep the water in a covered container.
Refrigerate if possible.
* Note: Certain organisms, such as Giardia and
Cryptosporidium, are known to be chlorine
and iodine resistant. Consequently, the heattreatment method may be more reliable
overall.
7
8
4.0 Regulatory Overview
Prior to 1974, each state ran its own drinking water
program and set standards that had to be met at the
local level. As a result, drinking water protection
standards differed from state to state. On December
16, 1974, Congress enacted the original Safe Drink
ing Water Act (SDWA). The SDWA was designed to
protect public drinking water supplies from “harmful
contaminants.” Congress gave EPA the authority to
establish acceptable or “safe” levels for known or
suspected drinking water contaminants and to design
a national drinking water protection program. Since
then, EPA has set uniform nationwide minimum
standards for drinking water by promulgating the
National Primary Drinking Water Regulations
(NPDWR) and Secondary Drinking Water Regula
tions (SDWR). State public health and environmental
agencies have the primary responsibility for ensuring
that the PWS meet federal drinking water quality
standards (or more stringent ones as required by the
state). [1]
Between 1974 and 1986, EPA developed MCL
standards under the NPDWR for 22 contaminants.
Since 1986, EPA has issued seven major rules that
establish standards for either a specific contaminant
(83 in total) or groups of contaminants.
In 1996, the SDWA was changed again. Among the
many changes to the SDWA, the 1996 amendments
added provisions to provide funding to communities
for drinking water mandates, focus regulatory efforts
on contaminants posing health risks, and added some
flexibility to the regulatory process.
To Find Out More About the SDWA:
www.epa.gov/safewater/sdwa/sdwa.html
www.epa.gov/safewater/regs/swtrlist.html
The EPA is now required to select at least five new
candidate contaminants to consider for regulation
every five years. This list of contaminants is known
as the Contaminant Candidate List (CCL). The new
law also requires EPA to set MCLGs for each
contaminant. MCLG is the level of a contaminant in
drinking water below which there is no known or
expected risk to health. MCLGs allow for a margin of
safety and are non-enforceable public health goals from
a regulatory perspective. EPA must then set an MCL as
close to the MCLG as is “feasible” using the best
available technology (BAT), taking costs into consid
eration (for MCL and MCLG definition, see box on
page 3).
The SDWA standards are enforced through federal
and/or state regulations requiring PWSs to test for
contaminants and install new types of treatment
technologies if the test results indicate the presence
of contaminants in the treated water.
To Find Out More About The MCLs and NPDWR:
www.epa.gov/safewater/mcl.html
EPA also publishes standards for nuisance contami
nants under the SDWR. The Secondary Maximum
Contaminant Levels (SMCLs) are concentration
limits for nuisance contaminants and physical
problems, such as offensive taste, color, odor,
corrosivity, etc. The secondary standards are not
enforced, and PWSs are not required to test for and
remove secondary contaminants. However, these
standards are useful guidelines for PWS operators
who want to ensure that their water will be suitable
for all household uses. Typically, water utilities
receive more complaints because their water tastes or
smells funny, so these secondary standards should not
be ignored.
To Find Out More About The SMCLs and SDWR:
www.epa.gov/safewater/consumer/2ndstandards.html
It is important to understand that the regulations you
are responsible for depends upon which category of
small system you fall under. There are approximately
170,000 community water systems (CWS) and noncommunity water systems (NCWS) in America.
NCWSs serve transient and non-transient populations
(see box on page 10). As you can see in Table 4-1,
small and very small systems account for the vast
majority of systems in the U.S. (>86%). [2]
PWSs derive their source water from both ground
and/or surface water. Table 4-2 describes the source
of water by system size and population served. As
you can see, the vast majority of systems use ground
water as their source of drinking water (153,697 vs.
14,136); however, the majority of people served are
drinking river and lake water (179.9 vs. 103.9
million). Also, almost 100% of non-community
systems are small.
Although the federal government defines “small
systems” as those serving fewer than 10,000 consum
ers, it also recognizes that there is a quite a difference
between the “larger” small systems and the “smaller”
9
There are two main categories of PWSs:
1) Community Water Systems (CWS) – CWSs
provide drinking water to the same people
year-round. Today, there are approximately
54,000 CWSs serving more than 250 million
Americans. All federal drinking water
regulations apply to these systems.
2) Non-Community Water Systems (NCWS) –
NCWSs serve customers on less than a yearround basis. NCWSs are, in turn, divided into
two sub-categories:
Non-transient (NTNCWS): Those that serve
at least 25 of the same people for more than
six months in a year but not year-round (e.g.,
schools or factories that have their own water
source); most drinking water regulations
apply to the 20,000 systems in this category.
Transient (TNCWS): Those that provide
water to places like gas stations and
campgrounds where people do not remain for
long periods of time; only regulations that
control contaminants posing immediate
health risks apply to the 96,000 systems in
this category.
[2]
ones that serve only a few hundred consumers. The
1996 SDWA Amendments mandated that information
about treatment technology performance and
“affordability” be developed for the following size
categories:
■
3,301–10,000 people (medium)
■
501–3,300 people (small)
■
25–500 people (very small)
Affordability criteria are based on a threshold of
2.5% of the median household income (MHI).
Nationally, the MHI is currently about 0.7% for the
three size categories (Table 4-3). Thus, any improve
ments to a small system cannot increase the annual
cost of drinking water per household beyond the
affordability threshold of 2.5% of the MHI. For
example, a drinking water system serving a popula
tion between 25–500 cannot put in improvements that
raise the annual cost per household by more than
$559 annually per household. [5]
The 1996 SDWA Amendments not only set in motion
the development of a variety of new rules, but a new
approach to setting future regulations. Of most
concern to small systems is that they are ultimately
going to be required to meet the same criteria that the
10
Table 4-1. Size Categories of Public Water Systems [2]
Percent of Community
Water Systems
System Size
(population served)
1980
1985
1990
1995
Very Small
(25 - 500)
67
63
63
61
Small
(501 - 3,300)
22
24
24
25
Medium
(3,301 - 10,000)
6
7
7
8
Large/Very Large
(>10,001)
5
6
6
7
Table 4-2. Distribution of Water Systems [2]
Surface
Water
Systems
People
Served
(millions)
Ground
Water
Systems
People
Served
(millions)
11,403
178.1
42,662
85.9
NTNCWS
821
.9
19,738
6.0
TNCWS
1,912
.9
91,298
12.0
System Type
CWS
larger, more affluent systems do. Table 4-4 provides
the general sample monitoring schedule for small
systems. Table 4-5 summarizes the current (2001)
and proposed regulations, their goal, and the specific
types and sizes of small systems affected. Note that
these requirements may vary by state and is depen
dent upon the size or type of PWS.
A full discussion of each of these regulations and its
requirements for specific systems is beyond the scope
of this document. The most common types of
violations are discussed in Section 5.0 of this handbook.
Table 4-3. National Level Affordability Criteria [5]
Baseline
MHI
($/year)
Water Bills
($/hh/year)
Water Bills
(% MHI)
Affordability
Threshold
(2.5% MHI)
Available Additional
Expenditure
($/hh/year increase)
25 - 500
$30,785
$211
0.69%
$770
$559
501 - 3,300
$27,058
$184
0.68%
$676
$492
3,301 - 10,000
$27,641
$181
0.65%
$691
$474
System Size
(Population Served)
MHI - median household income
hh - household
Table 4-4. General Sample Monitoring Schedule for Small Systemsa,b
Contaminant
Minimum Monitoring Frequency
Acute contaminants - Immediate risk to human health
Bacteria
Monthly or quarterly, depending on system size and type
Nitrate
Annually
Protozoa and viruses
Future requirements for the Ground Water Rule may require monitoring and
testing
Chronic contaminants - Long-term health effects if consumed at certain levels for extended periods of time
Volatile organics (e.g., benzene)
Ground water systems - quarterly for the first year, annually for years 2 and 3,
after that depending on results; surface water systems - annually
Synthetic organics (e.g., pesticides)
Larger systems, twice in 3 years; smaller systems, once in 3 years
Inorganics/metals
Ground water systems - once every 3 years; surface water systems - annually
Lead and copper
Annually
Radionuclides
Once every 4 years
a
General requirements may differ slightly depending on the State, size or type of drinking-water system.
Source: EPA Office of Ground Water and Drinking Water (OGWDW) web site.
b
11
Table 4-5. Small System Regulatory Summary [2] [6] [7] [8]
Regulation
Summary
What Systems are Affected?
Microbiological (National Primary
Drinking Water Regulations
[NPDWR])
Coliform MCL
All types and sizes
Volatile Organic Chemicals
(NPDWR)
MCLsb
All CWSs and NTNCWSs
Radionuclides
MCLsb
All types and sizes
Radon
MCLsb
All types and sizes
Inorganic Chemicals (NPDWR)
MCLs
All CWSs and NTNCWSs; transient
systems exempt except for
nitrates, nitrites
Total Coliform Rule
No more than 5% of samples positive for
Coliform; Distribution system sampling
All types and sizes
Surface Water Treatment Rule
3 Log (99.9%) removal of Giardia,
4 Log (99.99%) virus inactivation
Filtration treatment specified
All surface water and ground water
under the direct influence of
surface water
Lead and Copper Rule
Distribution System Action Levels
Arsenic
MCLs
Ground Water Rule
Appropriate use of disinfectants, multibarrier approach
All systems using ground water as
source
Long Term 1 Enhanced Surface
Water
2 Log removal (99%) of Cryptosporidium,
0.3 NTU for Turbidity; TOCc reductions for
precursor removal
All surface water and ground water
under the direct influence of
surface water
Filter Backwash Rule
Recycling filter backwash with treatment
All conventional (flocculation/
coagulation/sedimentation) and
direct filtration systems
Stage 1 Disinfectants/Disinfection
By-Products Rule (D/DBP)
Total Trihalomethane MCL reduced to 0.08
mg/L; 5 Haloacetic acidsd total of 0.060
mg/L; chlorite MCL 1.0 mg/L; bromate
0.010 mg/L MCL; maximum residual
disinfectant levels set (MRDLG/MRDL)
CWSs and NTNCWSs that use a
chemical disinfectant
Long Term 2 Enhanced Surface
Water Rule and Stage 2 D/DBP
Rules
To be enacted together to balance
microbial and disinfectant by-product
formation; Possible lowering of current
MCLs and distribution system
requirements
All types and sizes
Contaminant Candidate List (CCL)
Possible new MCLs
All types and sizes
a
b
b
Nephelometric Turbidity Unit
For MCL information, please visit: www.epa.gov/safewater/mcl.html
c
Total Organic Carbon
d
includes dichloroacetic acid, trichloroacetic acid, monochloroacetic acid, bromoacetic acid, and dibromoacetic acid
b
12
5.0 Common Violations
Generally, larger PWSs have more resources and
lower costs per customer to comply with regulations.
Thus, larger PWSs incur fewer violations, despite the
fact that larger PWSs have historically complied with
more regulations than smaller systems.
Small systems, however, account for the vast majority
of violations for both MCLs and M/R. According to
a 1993 survey, small treatment systems serving fewer
than 10,000 people represented 94% of all water
supply systems in America and served only 21% of
the national population. Also, these Small Systems
accounted for 93% of the MCL violations and 94% of
the M/R violations. The majority of the MCL
violations involved microbial parameters. M/R
violations could be the result of no sampling being
performed, insufficient recording of data, or failure to
report the data. The number of chemical contamina
tion violations were also exceedingly high for small
utilities. (See Tables 5-1 and 5-2 below).
EPA has also identified M/R violations associated
with human errors related to operators’ handwriting,
There are three main types of violations:
Maximum Contaminant Level (MCL) violation –
MCL violation occurs when tests indicate that the level
of a contaminant in treated water is above EPA’s or the
state’s legal limit (states may set standards equal to, or
more protective than, EPA’s). These violations indicate a
potential health risk, which may be immediate or longterm.
Treatment Technique (TT) violation - TT violation
occurs when a water system fails to treat its water in the
way EPA prescribes (for example, by not disinfecting).
Similar to MCL violations, TT violations indicate a
potential health risk to consumers.
Monitoring/Reporting (M/R) violation – M/R viola
tion occurs when a system fails to test its water for
certain contaminants, or fails to report test results in a
timely fashion. If a water system does not monitor its
water properly, it is difficult to know whether or not the
water poses a health risk to consumers.
[2]
Table 5-1. Total Coliform Bacteria Violations for the Period October 1, 1992 through December 31, 1994 [9]
Systems with Violations
Violations by Source Water
Number of
Consumers
Number of Systems
Percent of
Total (%)
Ground Water
Systems (%)
Surface Water
Systems (%)
<500
10,509
29.5
95.0
5.0
501 - 3,300
1,938
13.4
84.8
15.2
3,301 -10,000
592
14.4
71.8
28.2
> 10,000
487
14.4
59.1
40.9
Table 5-2. Chemical Contamination Violations for the Period October 1, 1992 through December 31, 1994 [9]
Systems with Violations
Violations by Source Water
Number of
Consumers
Number of Systems
Percent of
Total (%)
Ground Water
Systems (%)
Surface Water
Systems (%)
<500
531
1.5
96.4
3.6
501 - 3,300
162
1.1
73.5
26.5
3,301 - 10,000
25
0.6
60.0
40.0
> 10,000
15
0.4
33.3
66.7
13
such as the way a person records “D,” “P,” entries into
the reporting document.
In the past, this type of violation was one of the
leading causes for water systems being out of
compliance in the Commonwealth of Kentucky.
Recently, through a certification course, Kentucky
has provided handwriting suggestions to the small
system operators, which apparently have reduced the
number of M/R violations there. However, there is no
way to estimate the number of erroneous entries due
to penmanship. Operators should remember that a
hand-written report is only as good as the penmanship of the person filling out the document.
14
Small System operators need to take time and care
when filling out the reporting documents. The Com
monwealth of Kentucky identified hand-writing
problems associated with report forms for bacteriologi
cal analysis of water samples sent to various laborato
ries.
For example, Small System operators may first fill out
parts of the form. After analysis, the laboratory
(another person, company, etc.) completes the remain
ing information on the form and forwards a copy to the
state (primacy) agency. The portion the operator fills
out has a box to identify the type of sample collected.
Kentucky uses letter codes to identify the collected
sample: the two relevant codes are “D” for “distribu
tion” and “P” for “plant” sample. Each PWS is re
quired to send in an assigned number of “distribution”
samples each month. If an operator is not careful and
enters a “D” with a small tail, it can appear as a “P.”
Even though the primacy agency knows that the PWS
purchases water and does not even have a treatment
plant, the form still appears to have a “P” and will list
the water system as out of compliance (M/R) until the
Small System operator that filed the form makes
corrections.
6.0 Treatment Technologies
When the SDWA was reauthorized in 1996, it
addressed small system drinking water concerns and
required EPA to assess treatment technologies
relevant to small systems serving fewer than 10,000
people. The 1996 SDWA Amendments also identified
two distinct classes of treatment technologies for
small systems:
•
Compliance technologies, which may refer to:
(1) a technology or other means that is
affordable and that achieves compliance
with the MCL, and
(2) a technology or other means that satisfies
a treatment technique requirement.
•
Variance technologies that are only specified for
those system size/source water quality
combinations for which there are no listed
compliance technologies. [10]
Thus, listing a compliance technology for a size
category/source water combination prohibits listing
variance technologies for that combination. While
variance technologies may not achieve compliance
with the MCL or treatment technique requirement,
they must achieve the maximum reduction or inacti
vation efficiency affordable considering the size of
the system and the quality of the source water.
Variance technologies must also achieve a level of
contaminant reduction that protects public health.
Possible compliance technologies include packaged
or modular systems and point-of-use (POU) or pointof-entry (POE) treatment units. POU/POE systems
are discussed further in Section 7 of this handbook.
[11]
The 1996 SDWA Amendments did not specify the
format for the compliance technology lists and stated
that the variance technology lists can be issued either
through guidance or regulations. Rather than provide
the compliance technology list through rule-making,
EPA provided the listing in the form of guidance
without any changes to existing rules or passing new
ones. This guidance, which is summarized in Table
6-1, may be found in:
–
Small System Compliance Technology List for
the Surface Water Treatment Rule and Total
Coliform Rule (EPA 815-R-98-001)
–
Small System Compliance Technology List for
the Non-Microbial Contaminants Regulated
Before 1996 (EPA 815-R-98-002)
–
Variance Technology Findings for Contaminants
In anticipation of the states’ needs for innovative and
cost-effective small system treatment technology, the
EPA Water Supply and Water Resources Division
(WSWRD) has focused on the smallest of these
systems in the 25–500 population range and on those
technologies that are easy to operate and maintain.
WSWRD is a division of EPA’s Office of Research &
Development, National Risk Management Research
Laboratory. Alternative treatment systems/technolo
gies (package plants) are perceived as “high tech”
and are sometimes more expensive to purchase than
state-accepted conventional technologies. However,
in many cases, alternative treatment systems/
technologies are easier to operate, monitor, and
service, and less expensive to maintain and service
in the long-run.
Regulated Before 1996 (EPA 815-R-98-003)
A matrix of contaminants that are regulated under the
SDWA and possible treatment technologies for water
containing these contaminants are shown in Table 6-2.
Of the compliance technologies listed in Table 6-1, a
majority of the EPA WSWRD small systems research
has focused on evaluating “packaged” filtration and
disinfection technologies that are most useful to
small system operators. This handbook is a product of
ongoing research conducted by the WSWRD to
compile and evaluate the best available technology so
as to provide information about cost-effective
drinking water treatment technology options to the
small system operators. Filtration efforts have
focused on evaluating various bag filters, cartridge
and membrane filters. Disinfection techniques
evaluated included a variety of onsite chlorine
generators and packaged ultraviolet (UV)/ozonation
plants. Details regarding these efforts are presented
below.
Filtration
Filtration is the removal of particulates, and thus
some contaminants, by water flowing through a
porous media. Filtration is considered to be the most
likely and practical treatment process or technology
to be used for removing suspended particles and
turbidity from a drinking water supply. Federal and
state laws require all surface water systems and
systems under the influence of surface water to filter
their water. Filtration methods include slow and
rapid sand filtration, diatomaceous earth filtration,
direct filtration, membrane filtration, bag filtration,
and cartridge filtration. As discussed earlier, the
research at the EPA T&E Facility (Figure 1-1)
15
Table 6-1. Surface Water Treatment Compliance Technology Table [11]
Disinfection Technologies
Unit Technologies
Removals:
Log Giardia & Log Virus w/CT’s
indicated in ( )
Comment
Free Chlorine
3 log (104a) & 4 log (6)
Requires basic operator skills. Better for water systems with
good quality source water, low in organics and
iron/manganese. Concerns with disinfection byproducts.
Storage and handling precautions required.
Ozone
3 log (1.43) & 4 log (1.0)
Requires intermediate operator skills. Ozone leaks can be
hazardous. Does not provide residual disinfection protection
for distributed water. Concerns with disinfection byproducts.
Chloramines
3 log (1850) & 4 log (1491)
Requires intermediate operator skills. The ratio of chlorine to
ammonia must be carefully monitored. Requires large CT.
Ultraviolet Radiation
1 log Giardia (80-120), better for
Cryptosporidium, & 4 log viruses
(90-140) (mWsec/cm2 doses in
parentheses)
Requires basic operator skills. Relatively clean water source
necessary. Does not provide residual disinfection protection
for distributed water.
Chlorine Dioxide
3 log (23) & 4 log (25)
Requires intermediate operator skills. Better for larger
drinking water systems. Storage and handling precautions
required. Concerns with disinfection byproducts.
Filtration Technologies
Unit Technologies
Removals:
Log Giardia & Log Virus
Comment
Conventional Filtration and
Specific Variations on
Conventional
2-3 log Giardia & 1 log viruses
Advanced operator skills required. High monitoring
requirements. May require coagulation, flocculation,
sedimentation or flotation as prefiltration. Will not remove all
microorganisms.
Direct Filtration
0.5 log Giardia & 1-2 log viruses
(and 1.5-2 log Giardia with
coagulation)
Advanced operator skills required. High monitoring
requirements. May require coagulation, flocculation,
sedimentation, or flotation as prefiltration. Will not remove
all microorganisms.
Slow Sand Filtration
4 log Giardia & 1-6 log viruses
Requires basic operator skills. Most effective on high quality
water source. Will not remove all microorganisms.
Diatomaceous Earth Filtration
Very effective for Giardia (2 to 3log) and Cryptosporidium; low
bacteria and virus removal
Requires intermediate operator skills. Good for source water
with low turbidity and color. Will not remove all
microorganisms.
Reverse Osmosis
Very effective, absolute barrier
(cysts and viruses)
Requires intermediate to advanced operator skills, depending
on the amount of pretreatment necessary. Post disinfection
required under regulation. Briny waste can be toxic for
disposal.
Nanofiltration
Very effective, absolute barrier
(cysts and viruses)
required under regulation.
Ultrafiltration
Very effective Giardia, >5-6 log;
Partial removal viruses
required under regulation.
Microfiltration
Very effective Giardia, >5-6 log;
Partial removal viruses
on the amount of pretreatment necessary. Disinfection
required for viral inactivation.
Cartridge/Bag/Backwashable
Depth Filtration
Variable Giardia removal &
disinfection required for virus
removal
Requires basic operator skills. Requires low turbidity water.
Disinfection required for viral inactivation. Care must be
taken toward end of bag/cartridge life to prevent
breakthrough.
a
A 3 log (104) removal indicates that 99.9 % (or three 9’s) of Giardia was removed in 104 minutes of contact time (CT) with free
chlorine disinfection. Similarly, 1 log would indicate only one-9 removal i.e., 90% removal and a 4 log removal indicate 99.99%
removal. CT is a measurement of the length of time it takes for a disinfectant to kill, for example, giardia lamblia, at a specified
disinfectant concentration. If the disinfectant concentration is half the specified dosage in a CT table, the contact time should be
double the specified number in the CT table to ensure proper disinfection and vice-versa (twice the specified dosage requires only
half the contact time). CT requirements also assume there is sufficient mixing of the disinfectant and water and are dependent on
the pH and temperature of the water.
16
Table 6-2. Regulated Contaminant List (partial) and Possible Removal Technologies [10]
Microbial Contaminants and Turbidity
Turbidity (Suspended material)
Filtration
Coliform Bacteria, Viruses,
Cryptosporidium oocysts and Giardia
cysts
Turbidity reduction by filtration as noted above followed by disinfection
Radioactivity
Beta particle and photon activity
Mixed Bed Ion Exchange. Reverse Osmosis
Gross Alpha Particle activity
Treatment method depends on the specific radionuclide (e.g., radium, radon, or uranium)
Radium 226 and Radium 228
Cation Ion Exchange, Reverse Osmosis
Radon
Activated Carbon
Uranium
Anion Ion Exchange, Activated Alumina, Microfiltration, Reverse Osmosis
Health-Related Inorganic Contaminants
Antimony
Microfiltration, Reverse Osmosis
Arsenic (+3)
Reverse Osmosis
Arsenic (+5)
Submicron Filtration, Anion Ion Exchange, Activated Alumina, Reverse Osmosis
Organic Arsenic Complexes
Activated Carbon
Asbestos
Submicron filtration, Reverse Osmosis
Barium
Beryllium
Submicron Filtration & Carbon, Activated Alumina, Cation Ion Exchange, Reverse Osmosis
Cadmium
Submicron Filtration, Cation Ion Exchange, Reverse Osmosis
Chromium (+3)
Chromium (+6)
Anion Ion Exchange, Reverse Osmosis
Organic Chromium Complexes
Activated Carbon
Copper, Nickel
Fluoride
Activated Alumina, Reverse Osmosis
Lead
Cation Ion Exchange, Submicron Filtration & Carbon, Reverse Osmosis
Mercury (+2)
Cation Ion Exchange, Submicron Filtration & Carbon, Reverse Osmosis
Mercury (HgCl3 -1)
Organic Mercury Complexes
Activated Carbon
Nitrate and Nitrite
Selenium (+4)
Submicron Filtration & Carbon, Anion Ion Exchange, Activated Alumina, Reverse Osmosis
Selenium (+6)
Anion Ion Exchange, Activated Alumina, Reverse Osmosis
Sulfate
Anion Ion Exchange, Activated Alumina, Reverse Osmosis
Thallium
Cation Ion Exchange, Activated Alumina
Health-Related Organic Compounds
Use Activated Carbon or Aeration to Remove the Following Contaminants
Adipates
Benzene
Carbon Tetrachloride
Dibromochloropropane
Dichlorobenzene (o-, m-, p-)
1,2-Dichloroethane
1,1-Dichloroethene
cis- and trans-1,2-Dichloroethene
1,2-Dichloropropane
Ethylbenzene
Ethylene Dibromide
Hexachlorocyclopentadiene
Monochlorobenzene
Styrene
Tetrachloroethylene
Toluene
1,2,4- Trichlorobenzene
1,1,1-Trichloroethane
1,1,2-Trichloroethane
Trichloroethylene
Trihalomethanes
Use Activated Carbon to Remove the Following Contaminants
Alachlor
Aldicarb
Aldicarb Sulfone
Aldicarb Sulfoxide
Altrazine
Benzo(a)anthracene (PAH)
Benzo(a)pyrene (PAH)
Benzo(b)fluoranthene (PAH)
Benzo(k)fluoranthene (PAH)
Butyl benzyl phthlate (PAH)
Carbofuran
Chlordane
Chrysene (PAH)
2,4-D
Dalapon
Di (2-ethylhexyl) adipate
Dibenz(a,h)anthracene (PAH)
Glyphosate
Heptachlor
Epoxide Hexachlorobenzene
Indeno (1,2,3-c,d) Pyrene (PAH)
Lindane
Methoxychlor
Oxamyl
Pentachlorophenol
Picloram
Polychlorinated Biphenyls
Simarzine
2,3,7,8-TCDD (dioxin)
Toxaphene
2,4,5-TP (Silvex)
17
focused on “packaged” bag, cartridge and ultrafiltra
tion units. The other filtration methods typically use
natural filtration media (e.g., granulated media
particles, such as carbon, garnet, or sand, alone or in
combination). Bags and cartridge filtration media are
commonly made from synthetic fibers designed with
a specific pore size. The type of filter media most
suited for an application depends mainly on the
impurities present in the source (raw) water. Specifi
cally, the particle size of the impurity present in the
raw water typically dictates the type of filter media.
The particle sizes of common water contaminants and
the filtration devices required for their treatment (or
removal) are shown in Figure 6-1.
Operators should find a mechanism to filter particles,
turbidity or organic material out of the source water
and should realize that each particle removed by a
filter could be microscopic parasites such as the
Cryptosporidium sp. parasite. Removing particles
also allows the disinfectant to be more effective.
However, the best option would be to find a good
quality of source water, i.e., a source water that has
very low particle counts, turbidity, or organic material.
range with the membrane acting as a simple sieving
device. In ultrafiltration, nanofiltration, and reverse
osmosis processes, one stream of untreated water
enters the unit but two streams of water leave the
unit: one is treated water and the other is reject water
containing the concentrated contaminants removed
from the water. Microfiltration systems will remove
some microbes, such as protozoa and bacteria, but not
viruses. Unlike nanofiltration and reverse osmosis,
microfiltration cannot remove calcium and magne
sium from water. Ultrafiltration is used to remove
some dissolved material (such as large organic
molecules) from water. Particles down to 0.001 to
0.02 micron size range are removed. Most microbial
contaminants are removed including bacteria,
protozoa, and the larger virus sizes. Nanofiltration is
used to remove particles in the 0.001 to 0.002 micron
size range, polyvalent ions, and smaller organic
molecules (down to a molecular weight of about 200–
500 daltons). Reverse osmosis (RO) can remove
most contaminants dissolved in water including
arsenic, asbestos, protozoa, pyrogens, sediment, and
viruses. [12]
If the source water contains particle (large size)
impurities, prefiltration is generally applied in front
of bag or cartridge type filters. Prefiltration removes
the larger particulate material from the water stream
by using coarse, often back-washable granular media.
The prefilters protect the more expensive bag and/or
cartridge type units from frequent “fouling.” Figure
6-2 shows a picture of a clogged prefilter.
A source water may contain turbidity, particles, or
organic material. These materials consume and
compete for chemicals used in the treatment process,
such as chlorine. Thus, operators should find a
mechanism to filter the particles, turbidity or organic
material out of the water. Filtration can remove
certain types of color and particulate matter down to
any micron size. Special microfiltration devices or
submicron filters are capable of removing various
bacteria, viruses, and protozoa.
Bags and cartridge filters can be used to remove
contaminants down to approximately the 1-micron
particle size (1/10th the size of a human hair).
However, a prefilter (such as another bag or cartridge
filter of greater pore size) is typically recommended
prior to using a submicron filter. Microfiltration is
used to remove particles in the 0.5 to 10 micron size
0.001
Microns
0.01
Performance Evaluation of Filtration Media
Different vendors present filtration performance data
in different ways, leading to some confusion. For
example, the pore size specification for a filter can be
the absolute or nominal pore size. Absolute size
generally refers to a 100% removal of solids above
0.1
1.0
10
100
1000
(Log Scale)
Approx. Molecular Wt.
Relative
Size of
Common
Materials
Filtration
Technology
100
200
1000
10,000
20,000
100,000
500,000
Virus
Dissolved
Metal
Compound
Beach Sand
Bacteria
Tobacco Smoke
Pollen
Pesticide
Human Hair
Herbicide
Coal Dust
Salt
Crypt
ospor
idium
Reverse Osmosis
Ultrafiltration
Nanofiltration
Giarda
Cyst
Cartridge/Bag/Granular Filtration
Microfiltration
Figure 6-1. Particle Size Distribution of Common Contaminants and Associated Filtration Technology [13]
18
However, the mere presence of turbidity cannot be
directly related to the presence of microbial organisms; therefore, other measurements such as particle
counts might be performed.
Figure 6-2. Clogged prefilter.
the specified size rating on a single pass. Nominal
pore size generally refers to an average pore size of
the filter media itself and typically nominal values
indicate a certain percent removal of particles of the
specified size and higher.
Different filters have different operating pressure
ranges depending on the type of media, construction,
flow rates, etc. Filter performance may vary depend
ing on the change in pressures across the filter. As a
filter becomes clogged, the difference between the
pressure coming into the filter and the pressure
leaving the filter becomes larger and is a good
operational tool to determine when a filter should be
replaced, cleaned, or backwashed. Sudden change in
the exiting pressure can mean a bag or cartridge has
ruptured and is providing no protection. The high
pressure in the operating range typically indicates
that the media is clogged and the bag or cartridge
needs to be “washed” or replaced.
The performance of each filter can be judged based
on the removal of turbidity, particle-count, and
microbe (and/or surrogate) removal relative to its runtime. A number of evaluations have been conducted at
the T&E Facility using Cryptosporidium and/or
equivalent size micro-spheres (plastic beads).
Turbidity is defined as an “expression of the optical
property that cause light to be scattered and absorbed
rather than transmitted in straight lines through the
sample.” Simply stated, turbidity is the measure of
relative sample clarity or cloudiness (it is not associ
ated with color). When a light beam passes through a
sample of “turbid” water, the suspended solids scatter
the light, thus reducing the intensity of the light
beam. This reduction in intensity of the light beam is
measured optically/electronically using a turbidime
ter. Turbidity is reported in Nephelometric Turbidity
Unit (NTU); typically, the regulations require PWSs
to supply water with turbidity less than 0.50 NTU.
Particle counting involves counting each particle
individually in a sample of water. Various electronic
measuring devices are available that can be used to
count particles. One can imagine the difficulty
associated with manually counting thousands of
microscopic particles. Most particle counters have a
“sensing” zone that measures the particles individu
ally. As a particle is detected, it is sorted into a
“channel” based on magnitude (or size). Particle
counters are expensive ($20,000) and often difficult
to operate, thus limiting their usefulness to Small
System operators.
Also, different microbial organisms vary in size,
Cryptosporidium range between 3–7 micrometers in
size and Giardia range between 6–9 micrometers.
Typically, tests are performed to either measure the
actual Crytosporidium removal, the removal of test
surrogates, such as microspheres or naturally occurring spores. The surrogate is considered to be the
equivalent for Cryptosporidium removal. EPA
evaluated the performance of different types of
filtration media by operating various filtration
systems under various “test” conditions. The evalua
tion summaries for various types of filters are
presented in the following subsections.
Bag Filtration
Bag filtration systems are based on physical screen
ing processes. If the pore size of the bag filter is
smaller than the microbe, some removal will occur.
Depending on the quality of the raw water, EPA
suggests a series of filters, such as sand or multimedia
filters followed by bag or cartridge filtration, to
increase particulate removal efficiencies and to
extend the life of the secondary filter. Bag filters can
be used as a pre-filter to other filters as well.
Bag filters are disposable, non-ridged replaceable
fabric units contained either singly in series or
parallel or grouped together in multiples within one
vessel. The vessels are usually fabricated of stainless
steel (Figure 6-3) for corrosion resistance, strength,
cleaning, and disinfection. Supply (non-treated or
treated) water can be introduced into the vessel from
the top, side, or bottom, and flows from the inside of
the bag to the outside. Research conducted by EPA
has not shown any specific method of water introduc
tion into the vessel to be superior to others. However,
there are significant differences between manufactur
ers in the engineering design of closing devices and
gasket types used to seal the bag tightly into the
vessel and prevent filter by-pass. Each operator
19
EPA found that different bags, even with the same
stock and lot numbers, can exhibit a wide range of
water treatment capacity. Some bags may treat
many thousands of gallons of water while others
may treat only a few hundred gallons of water.
Thus, although bags may be rated similarly, their
performance can vary significantly, and bag selec
tion becomes more involved than a straightforward
matching of pore size and the size of the particle or
the turbidity to be removed from the water supply.
The selection of the best bag depends on the specific
water quality characteristics and treated water
(effluent) regulatory requirements or objectives.
oocyst. If the operator suspects oocysts are in the
filter, then the operator should wear proper personal
protective equipment to remove the filter. The filter
could then be placed in a secured location where it
can dry completely. The operator should then be able
to dispose of the filter normally.
Figure 6-3. Typical bag filter.
should be shown by the vessel vendor the proper fit of
the filter and lid to the body “housing” before
agreeing to purchase or set-up a bag filtration system.
Improper filter installation can cause water hammer
and can sometimes damage the bag. A vendor may
sometimes claim that improper bag “installation” was
the reason for poor performance of a bag filter (see
box on page 23).
Bag filters are designed in a variety of ways. They
can be fabricated of multiple layers and varying
materials. One of the most cost-effective benefits of
bag filters is their common use without costly
chemical additions, such as coagulation, flocculation,
or filter-coated chemicals. These filters have pore
sizes designed into them to contain and capture
oocysts, protozoa, or parasites Figure 6-4 is a picture
of a bag filter that has been cut away to view the
various layers and configuration. Caution should be
taken when handling spent filters due to the potential
concentration of the debris, protozoan, parasite, or
Figures 6-5, 6-6, 6-7 and 6-8 show rupture and bypass
scenarios. Ruptures in fabric and/or gaps in heat
welded bags can allow particles to pass through into the
treated drinking water (as shown in Figure 6-5, with a
pen inserted to mark the tear, and in Figure 6-6). A
bypass is typically associated with significant
discoloration of the bag. Figure 6-7 shows discolora
tion on both ends of the bag filter. The most common
location for bypass is generally near the lid of each
filter housing as shown in Figure 6-8.
EPA has evaluated several types of bag filters at the
T&E Facility. Different configurations of bag
filtration systems (see Table 6-3 and Figure 6-9) were
challenged under controlled turbidity levels and flow
rates. The research was not intended to compare
systems but to identify the most important design and
operational characteristics that provide for the most
economical application in various raw water situa
tions. Important design considerations are bag
quality, gasket integrity, and hydraulic reliability.
Operational factors include continuous vs. intermittent operation, flow rate, and pressure differential.
Turbidity challenges ranged from 1 NTU to 10 NTU.
Table 6-3. Bag Filter Characteristics (see Figure 6-9)
Bag Filter
20
Pore Size
# of Layers
Surface Area (sq. ft)
Seam Const.
1
3 micron (average)
9
41
Sewn
2
3 micron (average)
1
2-3
Sewn
3
99 % removal of 2.5 micron
95 % removal of 1.5 micron
18
35
Sewn
Hole
Figure 6-6. Bag filter showing fabric rupture.
Figure 6-4. Cut-away of bag filter.
Average % reduction ranged from 40% to 93%. Of
course, at higher influent turbidity levels, greater
removals can be demonstrated but there seems to be a
“best” (e.g., 0.50 NTU) turbidity level that each brand
of bag filter can reach regardless of the initial influent
quality.
During initial start-up, removal was better and then
settled into a fairly steady performance rate until near
the end of the bag’s life. Flow rate and starting water
quality (or lack of) did not seem to be a major factor
in filter performance. Once a bag begins to foul at 5
to 10 pounds per square inch (psi) differential, the
time until the bag must be replaced quickly decreases. High NTU scenarios (>5 NTU) indicate the
need for multiple filtration barriers in order to not be
bankrupted by having to buy replacement bags every
few days. Bag rupture is more likely near the end of
the filter run as the pressure differential reaches its
maximum. Once a rupture or hole occurs, the
Figure 6-7 and 6-8. Bag filters showing discoloration
associated with bypass.
Bag Filter
#3
Bag Filter
#1
Bag Filter
#2
Figure 6-5. Bag filter showing rip in seam (where pen is
inserted).
Figure 6-9. Different configurations of bag filters tested.
(see Table 6-3)
21
treatment barrier is gone with effluent water quality
the same or worse than influent. The results indicate
that for systems with little water storage, or without onsite/automatic operator control to stop flow at this point,
it is critical to be conservative in estimating bag life.
Particle count analyses were also performed simulta
neously. Figure 6-10 demonstrates that during the
experiment, one of the bags removed nearly all
particles greater than 8 micron in size, although not
immediately after installation. All bags in the study
were rated with average pore sizes in the 2-5 micron
range. Thus, a Small System operator must be aware
that pore size only provides a general idea of the
filter’s capability. The raw water used in these
experiments exhibit a majority of small (1-3 micron)
particles whereas other water sources with turbidity
made up of larger particles may be filtered better by
bag filtration. Another operational characteristic
observed for all filters was an initial loss of removal
efficiency and pressure differential when first turned
on after having been out of operation for several
hours. Within approximately 30 minutes, removal
and pressure differential returned to the levels of the
previous day. [14]
A fourth bag was initially tested with a 1 micron
absolute pore size, 1 layer, and heat-welded seems
but could only run for a few hours before becoming
clogged. It could however be used in series following
one of the other bags.
Figure 6-10. Influent vs Effluent Particle Counts
through the bag layers and ultimately pass through.
Bag filtration should not be used as a single barrier to
remove parasites, such as Cryptosporidium. However, it can be used as a pretreatment step before
cartridge filtration to remove large particles and high
levels of turbidity to improve parasite removal and
then polish or treat with a disinfectant to remove any
microbial or bacterial contaminant.
Cryptosporidium challenges were also conducted
along with the beads. Table 6-4 summarizes all the
contaminant challenges that took place over a range
of flow rates, pressure differentials (bag age), and raw
water loadings. Although Bag 3 showed the highest
removal rates, it varied considerably during filter runs
and was the most likely to experience a rupture. Bag
1 was extremely steady in its removal and would
probably be easier to operate over time. [15]
Figures 6-11 and 6-12 show the inner structure of a
new and used bag (as viewed under an electron
microscope). It appears that as a bag continues to be
used, the smaller particles (dirt) can work their way
Figure 6-11. New bag.
Table 6-4. Bag Filtration Performance Summary [15]
Percent Reduction
Beads or
Microspheresa
Turbidity
Particle Countb
Bag 1
93%
80%
95%
94%
Bag 2
50%
10%
10%
40%
Bag 3
99.1%
93%
97%
99.94%
Bag Filter System
a
4.5 micron plastic beads
4 to 6 microns
b
22
Cryptosporidium
Bag and Cartridge Filter Observations
Vendor support for systems can vary significantly
based on the experience of the representative
contacted. One vendor insisted on the use of a
special “installation” tool for proper bag filter
operation. The special tool turned out to be a
baseball bat!
Seasonal variability in source water quality may
significantly impact the life of the bag/cartridge
filter. For surface water systems, influent turbidity
may increase dramatically following rain.
Figure 6-12. Dirty bag.
Cartridge Filtration
Cartridge filters are a technology suitable for remov
ing many microbes and reducing turbidity. These
filters are easy to operate and maintain, making them
suitable for treating low-turbidity water. They can
become fouled relatively quickly and must be
replaced with new units. Although these filter
systems are operationally simple, they are not
automated and can require relatively large operating
budgets. A disinfectant may be recommended to
prevent surface-fouling via microbial growth on the
cartridge filters and to reduce microbial pass-through.
Figure 6-13 shows a cartridge filter and housing.
air release valve. The typical housing has a topplacement lid, which seals with an o-ring and is
clamped or bolted into place after a filter has been
inserted (Figure 6-13).
Inlet and outlet pressure gauges are used to determine
filter status. The pressure drop is measured and used
to indicate when the life of the filter has expired. It is
important to adhere to the manufacturer’s recom
mended pressure drops for replacement/cleaning to
prevent break-through and contamination of the
treated water. Figure 6-14 shows dirty and clean
cartridge filters.
Cartridge filters can be “ganged”, i.e., bundled
together, or set up in various single configurations.
The units can be contained either singly in series or
parallel or ganged together in multiples within one
Cartridge filters are rigid cores (usually PVC) with
surrounding deep-pleated filter media much like a
Shop-Vac™ air filter. They are available in various
pore sizes and materials depending on the intention of
filtration and the source water quality. The filter
media are typically constructed of Polypropylene or
Polyester but may be of other fibers for specific
applications. Pore sizes available may vary by
vendor and material, but are typically 100, 50, 25, 10,
5, and 1 micron. Cartridge filters may be disposable
or washable depending on the material and vendor.
Depending on the inlet water quality, flow rate, and
filter pore size, a filter may last from one hour to
longer than a month. If inlet water quality is poor, a
pre-filtration step may be best to reduce filter changes
and minimize cost. This can be achieved by using one
cartridge filter system with a 50 or 25 micron filter for
pre-filtration, followed by another cartridge filter
system with a 5 or 1 micron filter for finer filtration.
Cartridge filter housings are generally made of
stainless steel or fiberglass-reinforced-plastic for
chemical resistance. The housings may be equipped
with one or two pressure gauges, drain ports, and an
Figure 6-13. Cartridge filters and housings.
23
Table 6-5. Cartridge Filter Characteristics
Cartridge
Filter
Pore
Size
Construction
Surface
Area (sq. ft.)
Cartridge 1
1 micron
Vertical Pleated
30
Cartridge 2
1 micron
Vertical Pleated
40
2 micron
Compound Radial
Pleated
117
Cartridge 3
Figure 6-14. Dirty and clean cartridge filters.
vessel. Like bag filters, cartridge filters can be
designed for a variety of filtration applications. Most
times the cartridge filter is used as a polishing filter
following coarse sand filtration or bag treatment
technologies. Again, like bag filters, one of the most
cost-effective benefits of the cartridge filter is that it
is commonly used without costly chemical additions,
such as coagulation, flocculation, or filter-coated
chemicals. Like bag filtration technology, cartridge
filters are designed to capture protozoa, parasites, or
oocysts. These filters have “absolute” pore sizes
designed and engineered into them that are reported
to be uniform to contain and capture oocysts, protozo
ans, or parasites. At the same time, these filters permit
bacteria, viruses, and fine colloids to pass through.
Figure 6-15. Normal cartridge filter.
Figure 6-15 shows a filter without internal structure
failure. Figure 6-16 shows the filter after water ham
mered the filter and caused the unit to collapse. These
figures of the cartridge filter demonstrate that cartridge
filters can be damaged under certain types of operation.
EPA has evaluated several types of cartridge filters at
the T&E Facility (see Table 6-5). Please note that the
performance of the filters varies widely with the inlet
water flowrate, inlet turbidity and particle size. A
presentation of performance data that represents a full
range of test conditions is beyond the scope of this
document. However, a summary of these evaluations
is presented in Table 6-6.
Membrane Filtration [13]
Membranes act as selective barriers, allowing some
contaminants to pass through the membrane while
blocking the passage of others. Membranes may be
made from a wide variety of polymers consisting of
several different materials for the substrate, the thin
film, and other functional layers of the membranes.
The thin film is typically made from materials like
24
Figure 6-16. Collapsed cartridge filter.
cellulose acetate that have tiny pores that allow the
passage of water while blocking bigger molecules.
The movement of material across a membrane
typically requires water pressure as the driving force.
There are four categories of pressure-driven mem
brane processes: microfiltration (MF), ultrafiltration
(UF), nanofiltration (NF), and reverse osmosis (RO).
(PDCO), which is the diameter of the smallest particles it
retains, typically in the range of 0.1 to 10 microns. UF is
used for separating large macromolecules, such as
proteins and starches in other industry sectors. Sometimes, UF membranes are classified by the molecular
weight cut off (MWCO) number. MWCO is defined as
the molecular weight of the smallest molecule, 90% of
which is filtered by the membrane. The range of UF
systems typically spans between 10,000 to 500,000
MWCO.
Table 6-6. Cartridge Filtration Performance Summary
Percent Reduction
Filter System
Turbidity
Particle Count
Cartridge 1
50% - 80%
80% - 96%
Cartridge 2
77% - 88%
89% - 96%
Cartridge 3
70% - 89%
>99%
Membrane filters (such as MF and UF) act as sieves,
much like the bag and cartridge filters, just with smaller
pore sizes (0.003 to 0.5 microns). Other membrane
systems, NF and RO, actually block contaminants
dissolved in water down to the molecular level. RO and
NF processes are typically applied to remove dissolved
contaminants, including both inorganic and organic
compounds, and these processes operate at pressures
significantly higher (e.g., 800–1500 psi) than MF and
UF. Low-pressure membrane processes (i.e., MF and
UF) are typically applied to remove particulate and
microbial contaminants and can be operated under
positive or negative pressure (i.e., vacuum pressure).
Positive-pressure systems typically operate between 3
and 60 psi, whereas vacuum systems operate between -3
and -12 psi. There is no significant difference between
the range of pressures at which MF and UF systems
operate. EPA has evaluated both MF and UF systems.
The performance summaries for both systems are
presented in Table 6-7.
When UF membranes begin to clog, a pressure drop
between the inlet and outlet will occur, along with a
reduction in flow rate. Adjustments should be made to
the raw inlet valve and reject water valve to maintain
flow as the membrane fouls. UF membranes must be
periodically backwashed according to their rated
pressure drops. It is important to follow manufacturer’s
recommended pressure drops for backwashing and/or
manual cleaning to prevent permanent fouling, breakthrough or pressure build-ups. Membranes are typically
cleaned with high concentrations of chlorine, acid, or
bases. These are typically the only chemicals used for
these systems thus reducing operator attention from that
required for coagulation and flocculation.
EPA has conducted UF research studies at the T&E
Facility using a spiral wound membrane package plant.
The UF system had a nominal pore size of 0.005 mm
with a MWCO of 10,000. This package plant can treat
water at flow rates up to 15 gallons per minute (gpm).
Figure 6-17 depicts the UF system operated at the T&E
Facility. The results of these studies are included in
Table 6-8.
Ultrafiltration
Ultrafiltration (UF) systems are effective for remov
ing pathogens, while being affordable for small
systems. Ultrafiltration is one of many processes
used to remove particles and microorganisms from
water. The ultrafiltration technology falls between
nanofiltration and microfiltration on the filtration
spectrum. Systems may be designed to operate in a
single pass or in a recirculation mode.
Studies were conducted to determine the efficiency of
the UF system to remove Cryptosporidium-sized
particles (4.5 micron plastic beads termed
“microspheres”). Initial testing showed an unacceptable
99.5% removal of the microspheres. However, there
was no indication from flow, pressure, or turbidity that
the spiral wound system was not properly removing the
microspheres. Maintenance/inspection of the mem
branes showed a crack in a plastic adaptor between the
membranes and the downstream end of the permeate
tube (see Figure 6-17[b]); this crack allowed raw water
to pass directly into the finished water. Figure 6-18
shows a photograph of the cracked adaptor. The
malfunctioning unit did not demonstrate any problems
with pressure losses through the membrane due to the
UF systems are operated by pumping water through a
recirculation loop containing the membrane housing,
and through several membranes, which are usually
positioned in series. The UF membranes are usually
large cartridges (EPA studied 8" x 40" cartridges) that
can range in pore size from 0.003 to 0.1 microns. They
are usually constructed of plastic material. These can be
hollow-fiber or spiral-wound membranes. The mem
branes are also classified by pore diameter cut off
Table 6-7. Membrane Filtration Performance Summary [15]
Percent Reduction
Filter System
Microspheres
Particle Count
Cryptosporidium
MS2 Bacteriophages
MF System
99.95 - 99.99
99.985 - 99.914
99.957
NA
UF System
99.3 - 99.998
94 - 99.91
99.95 - 99.994
99.99
25
Table 6-8. Filtration Summary Table (as tested)
Average
Cryptosporidium
Removal (%)
Filter Size
(microns)
Flow Rate
(gpm)a
Purchase
Price ($)
90.0
1+
Up to 40
2,000
50/bag
Hours/days/weeks
Cartridge Filter
90 - 99.0
0.5+
up to 100
2,000
50-300/cartridge
Hours/days/ weeks
UF Membrane
99.9 - 99.99
0.005 - 1
up to 30
50,000
5,000/element
Up to 3 years
Technology
Bag Filter
Filter Replacement Cost ($)
Expected Filter Life
a
gpm = Gallons per minute
plastic adaptor shown
cracked in Figure 6-18
(b)
Figure 6-17.
(a) UF System
(b) UF System Cartridges in Series
(c) UF System Cartridge Cut-Out
cracked adaptor and showed acceptable turbidity
removal results. Small system operators should be
aware that EPA has also observed and identified this
situation in the field. Each observance was related to
improperly installed UF filters, broken o-rings, or
(cracked) adaptors. After each of the units was repaired,
results indicated up to 99.998% removal of
microspheres using the UF treatment package plant.
Cryptosporidium sp. was also injected into the feed
supply water to the UF package plant. Under laboratory
conditions, the UF plant achieved a removal of 99.95%
to 99.994%. A test was conducted using bacillus spores
to simulate cyptosporidium removal. These tests
showed removals similar to that obtained in the tests
using cryptosporidium (about 99.99%).
(a)
(c)
with an overall removal average of 99.5% (Figure 6-19).
As a comparison, Cryptosporidium filtration achieved a
removal of 99.5% oocysts, which was very similar to the
average log removal of the 4.5 microns standardized
plastic test beads.
However, the last data point in Figure 6-19 is shown in
detail in Figure 6-20. This data point represents samples
Twenty-four studies were performed at an average inlet
pressure of 29 psi; the effluent flow rate averaged 7.2
gpm. The sample collection duration of each test ranged
from 218 to 5,532 minutes with an average of 1,110
minutes. The system was operated continuously and
was purged with tap water at least 8 hours between each
test run. Results indicated a 99.9% to 99.99% removal
range of microspheres from the influent to the permeate, Figure 6-18. Cracked plastic adaptor used
between membranes.
26
It should be noted that although Cryptosporidium is
4-6 microns in size, it can still pass through an
absolute 3-micron size filter by deforming and
squeezing through. The pliability of Cryptosporidium
is demonstrated in Figures 6-21 (a) and (b).
Figure 6-19. Log removal of beads vs. membrane
run-time.
Figure 6-21a. Cryptosporidium oocyst on upper surface of
3 micron pore.
Figure 6-20. Number of Beads in Effluent vs Run
Time
being taken from the permeate over almost four days
compared to just one day for the other data points shown
in Figure 6-19. After 5,532 minutes (approximately
3.84 days) of run time, plastic test beads were still found
in the permeate even though influent spiking had
occurred over a two-hour period at the beginning of the
experiment four days earlier. Removal was 99.5% for
the individual experiment, lower than most of the
previous experiments. The higher removal rate achieved
by the shorter experiments could be the effect of
insufficient sample collection time, and suggests that
particles may have long residence times in membrane
filters but are still capable of ultimately passing through.
Figure 6-21b. Cryptosporidium oocyst coming through
3 micron pore.
Tests were also conducted to evaluate the effectiveness
of the UF system in removing a virus. MS2 bacterioph
age was used in the experimental runs to simulate a
particle similar in size to a virus. The test conditions
were similar to the conditions used for the
cryptosporidum tests. There were no MS2 bacterioph
ages detected in the permeate from the UF. However,
this is a likely result of the sampling technique used
since the permeate could be examined in discrete
intervals only because of the small size of the MS2
bacteriophage. (In the cryptosporidum study, a portion
of the permeate was constantly filtered to catch any
particles. In this study, this was not possible because a
filter to catch the MS2 bateriophages is not available).
Figure 6-22. Micro Filtration System.
27
United States Forest Service—Hybrid Filtration/
Disinfection System (see Figure 6-24)
A hybrid filtration/disinfection system was commis
sioned by the United States Forest Service San Dimas
Technology and Development Center in Los Angeles,
California, as a follow up to EPA’s bag filtration and onsite chlorine generation studies. This system incorpo
rated bag or cartridge filters prior to an on-site chlorine
generator onto a skid specially designed for intermittent
operation at campgrounds. The skid was designed to fit
into the bed of a pickup truck capable of being lifted
and installed manually (four people) at the campground.
An ion-exchange softener was included on the skid to
produce brine-free water to maintain pump operation.
The system was also designed for remote monitoring
and control, and solar power with battery backup.
Based on the campground needs, it was determined that
cartridge filtration was preferable and more economical
because of the low turbidity in the raw mountain water
and the desire for a better Cryptosporidium and Giardia
barrier.
In-house research at the San Dimas facility concluded
that the cartridge filters can achieve 99% (2 Log)
removal of Giardia-sized particles (5- to 15-micron
size) in low-turbidity (<0.60 NTU) raw waters. Inter
mittent operation did not appear to cause any additional
problems, nor did there appear to be any loss in removal
efficiencies immediately after the system was turned
off. The removals were achieved 95% of the time, and
the system was able to function beyond the 20-psi
differential pressure between raw and finished sampling
points (that determines cartridge life). The cartridge
filters were able to handle short-term spikes, although
algae blooms in raw water resulted in short filter life
and early filter failure. Particle-counting instruments
also proved problematic.
Thus, it is assumed that the UF system effectiveness in
removing MS2 bacteriophages is similar to that
observed during the cryptosporidium study, or about a
99.99% removal.
Microfiltration
Various field evaluations have been conducted to
assess the operational performance of microfiltration
technology and provide information about the
removal of physical and biological contaminants
under continuous operation. Figure 6-22 shows a
typical MF unit. Microfiltration membranes nor
mally have pore sizes 0.1 microns or greater [16].
The water flow of the test system ranged between 15
and 34 gpm. Standardized plastic test beads of 4.5
microns were injected into the raw untreated test
water. The reduction of turbidity was 93.33% and the
reduction of Cryptosporidium was 99.957%. Particle
counts were performed resulting in removals of
99.985% for particles in the 4-6 micron range and
28
In anticipation of small system needs in meeting the
Stage 1 Disinfectants/Disinfection Byproducts Rule, the
Ground Water Rule, and the Stage 1 Enhanced Surface
Water Treatment Rule, the WSWRD has investigated
alternative technologies focusing on their ability to
inactivate Cryptosporidium while at the same time
being affordable and easy to operate and maintain.
99.914% for particles in the 1-25 micron range. Thus,
even though the plastic test beads have a diameter of
4.5 microns, beads are seen to pass through the
membrane (or through seals, adapters, or gaskets) even
within the 1 to 4 micron range. Collectively, results
showed no influence due to the different flow rates.
The results indicate that microfiltration technology is a
feasible small system drinking water treatment technol
ogy for particle removal [13].
Note that the final turbidity achieved by a UF system
was <0.2 NTU regardless of the influent turbidity. Thus
percent removal does not provide a meaningful measure
of UF performance for turbidity. This is not, however,
true for MF systems where the effluent turbidity is
dependent on the influent turbidity. The MF systems
tested at T&E achieved removals of 90% to 98% with
finished turbidity levels ranging between 0.1 to 0.6 microns.
A real-world case study and example of a UF System
package plant is included in Section 9 of this document.
Filtration Summary
As discussed previously in this section, EPA has
evaluated several types of filtration systems at the T&E
Facility and various field locations. The operating
conditions, microbe (Cryptosporidium) removal
efficiency, initial and operating cost for the individual
units vary widely. Table 6-8 presents a summary of
information for each type of filter.
Based upon the above technology investigations, it
appears that there are several alternative filtration
technologies. Depending on raw water characteris
tics, a likely configuration can consist of filters in
series with decreasingly small pore sizes that can, in
effect, remove most microbiological contaminants,
reducing the need for chemical coagulants and
disinfectants. Operation and maintenance would be
simplified, thus enhancing long-term compliance.
Disinfection
Disinfection is the process used to reduce the number of
pathogenic microbes in water. The Surface Water
Treatment Rule (SWTR) [18] requires PWSs to disinfect
water obtained from surface water supplies or ground
water sources under the influence of surface water. The
proposed Ground Water Rule may require PWSs to
disinfect their well water supplies. MCL and M/R
violations of the SDWA and its amendments over the
performs poorly in removing viruses (such as enterovirus
and hepatitis A) and protozoa (such as Cryptosporidia
and Giardia).
Several guidance manuals are available to help PWS
operators comply with the Stage 1 Disinfectants/
Disinfection Byproducts Rule. Examples of such
guidance manuals include:
■ Disinfection Profiling and Benchmarking
Guidance Manual (EPA 815-R-99-013), August
1999.
■ Alternative Disinfectants and Oxidants Guidance
Manual (EPA 815-R-99-014), April 1999.
■ Microbial and Disinfection Byproduct Rules
Simultaneous Compliance Guidance Manual
(EPA 815-R-99-015), August 1999.
years show that small systems are either (1) unable to
simply disinfect their water or (2) record and submit their
data to the appropriate oversight agency. Typically,
some form of chlorine is used as a disinfectant. More
recently, ultra-violet (UV) radiation, Ozonation (O3) or a
combination of UV/O3 technologies are being used for
disinfection.
Ozonation is another disinfection method. Ozone is
effective as an oxidizing agent in removing bacteria with
a relatively short exposure time. Ozone generators are
used to produce ozone gas on site, since the gas is
unstable and has a very short life. These generators must
be installed and monitored cautiously, because high
concentration levels of ozone will oxidize and deterio
rate all downstream piping and components. With home
ozone systems, leftover ozone must be removed with an
off-gas tank to ensure homeowners are not exposed to
ozone gas, which is a strong irritant. High levels of
ozone are extremely harmful especially in enclosed or
low-ventilation areas. Ozone also forms highly carcino
genic DBPs with bromide to form bromate, broform,
dibromeacetic acid, and others. Thus, there is no “silver
bullet” for disinfection that does not have some drawbacks. In PWSs, UV equipment or biological filters are
typically installed to remove ozone residuals prior to
filtration.
On site ozone generating equipment is costly compared
to other disinfection technologies. The effectiveness of
the forms of chlorine and ozone in killing microorganisms (i.e., biocidal efficiency) varies with the type
of micro-organism and the water quality conditions
(such as pH). The relative effectiveness of chlorine and
ozone in killing microbes and the stability of each
disinfectant is summarized in Table 6-9.
The use of chlorine as a disinfectant is commonly
accepted worldwide. Chlorination is a popular choice
because of its residual disinfection characteristics. Its
effectiveness is very simple to test; one need only
measure the residual chlorine at the point of consump
tion to ensure proper disinfection. Test procedures for
measuring chlorine are presented later in this section.
However, people are becoming more concerned about
the disinfection by-products (DBPs) of chlorine and are
looking for alternatives. Chlorine reduces bacteria, but
it also reacts with other organic impurities present in
water producing various trihalomethanes (THMs) which
are listed as probable or possible human carcinogens
(cancer-causing agents). Other disadvantages of
chlorination are undesirable tastes and odors, require
ment of additional equipment (such as tanks) to
guarantee proper contact time, and extra time to monitor
and ensure proper residual concentration level. It also
The use of UV light as means of water disinfection has
been a proven process for many years. The benefit of the
UV disinfection process is that it does not use any
chemicals and appears to be effective for Cryptosporidium.
However, residual disinfection (to account for contami
nation via the distribution system) is not possible.
Operators need to use the optimum amount of
disinfecting agent to achieve appropriate disinfection
and minimize DBP formation. Currently, the regu-
Table 6-9. Summary of Disinfectant Characteristics Relating to Biocidal Efficiency [19]
Ranka
Disinfectant
pH Effects on Efficiency
(pH ranges 6-9)
Biocidal Efficiency
Stability
Ozone
1
4
Little effect
Chlorine dioxideb
2
2
pH increase is beneficial
Free chlorineb
3
3
pH increase is detrimental
a
b
1 = best, 4 = worst.
Ranking influenced by pH.
29
lated DBPs in the United States are trihalomethanes
(THMs) with a maximum contaminant level of 80 parts
per billion (ppb). However, the practice of chlorination
for pre-oxidation or for disinfection can result in the
formation of chlorinated organic by-products. The
recently promulgated Disinfectant/Disinfection
Byproducts (D/DBP) Rule will result in the regulation
of several other by-products of chlorination, such as
haloacetic acids (HAA5) (to 0.060 mg/L), along with a
potential reduction in the current THM standard of 80
ppb (Federal Register, 1998). In some cases this might
result in a change to an alternative pre-oxidant, or
disinfectant, use of membranes, or elimination of the
use of free chlorine [9]. To minimize the formation of
DBPs, under the SWTR [18] and the proposed Enhanced
Surface Water Treatment Rule (ESWTR) [20] most
utilities are also required to filter their water unless the
following conditions are met in the surface water prior
to disinfection:
•
fecal coliform bacteria <20/100 milliliters (mL)
in 90% of samples,
•
total coliform bacteria <100/100 mL in 90% of
samples,
•
turbidity <5 NTU, and
•
other MCLs met.
Treatment plants exempt from filtration must disinfect
to achieve 99.99% inactivation of viruses, and 99.9%
inactivation of Giardia lamblia cysts. For systems that
use chlorine for disinfection, compliance with these
requirements must be demonstrated with the CT
approach (the product of the average disinfectant
concentration and contact time). CT values estimated
for actual disinfection systems must be equal to or
greater than those published in the SWTR Guidance
Manual for viruses and G. Lamblia cysts respectively [9].
For a List of CT Values, go to:
www.epa.gov/safewater/mdbp/pdf/profile/benchpt4.pdf
Also, EPA studies have demonstrated that the pliabil
ity of Cryptosporidium oocysts may permit the
oocysts to pass through a filtration system, thus
making disinfection that much more important as a
barrier [17]. Just like large systems, small systems
have to be even more concerned with the safety and
ease of handling, shipping, storage, and the capital,
and operation and maintenance (O&M) costs associ
ated with the use of appropriate disinfectant technology.
EPA has evaluated several disinfection technologies
that are affordable and easy to use from a small
systems perspective. An evaluation summary of these
technologies is presented in the following subsec
tions.
30
Chlorine Residual and Monitoring [9]
As identified earlier, chlorination is preferred for
disinfection at small treatment plants and for small
utilities. The following four methods are popularly
used to monitor residual (free and total) chlorine in
treated water supplies:
1. N,N-diethyl-p-phenylenediamine (DPD)
colorimetric method
2.
Iodometric method,
3.
Polarographic membrane sensors, and
4.
Amperometric Electrodes
The DPD colorimetric method is most commonly used
and is based on the American Society for Testing and
Materials (ASTM) Standard Method. In this method,
DPD is oxidized by chlorine to form two oxidation
products with one product being darker in color than
the other. The color intensity is measured by either a
colorimeter (color wheel) or spectrophotometer and
corresponds to the amount of free and total chlorine
present in the sample. This method can measure both
free and total chlorine.
The Iodometric method involves adding potassium
iodide to a water sample to react with the available
chlorine to form iodine. The amount of free iodine
generated is monitored and correlated to the amount
of chlorine present. Since this method does not
distinguish between free and combined chlorine, it
should only be used when monitoring for total
chlorine.
The Polarographic Membrane sensor method consists
of a pair of electrodes that monitor free chlorine. The
electrodes are immersed in a conductive electrolyte
and isolated from the sample by a chlorine-permeable
membrane. Free chlorine diffuses through the
membrane and is reduced to chloride on the surface of
the electrodes, generating a flow of electrons between
the two electrodes. The current generated is propor
tional to the concentration of the free chlorine.
Amperometric Electrodes method consist of two
combination probes that use a platinum cathode and a
silver anode to amperometrically measure free chlorine
along with pH and temperature. Within these elec
trodes, an electrochemical reaction occurs based on
the available chlorine concentration, generating a
proportional current. This method can measure free
chlorine.
EPA found the cost of the various sensors to range
from $400 to over $10,000 for stand-alone, sophisti
cated sensors that were automated and combined
multiple monitoring parameters. A standard, online,
process control instrument with sampling assembly
and analyzer ranged in cost from $2,000 and $10,000.
Disinfection by Chlorination
Chlorine is generally obtained for disinfection in the
form of gaseous chlorine, onsite chlorine dioxide
generators, solid calcium hypochlorite tablets, or
liquid sodium hypochlorite (bleach). Gaseous
chlorine and onsite chlorine dioxide generators are
typically found at larger drinking water systems.
Small drinking water systems sometimes use solid
calcium hypochlorite, which is typically sold as a dry
solid or in the form of tablets for use in proprietary
dispensers. This method of disinfection is, however,
expensive, suitable mainly for low flow applications,
and the use of calcium can lead to scale formation.
For the most part, small system operators continue to
disinfect water using common household liquid
bleach or swimming pool chlorine.
There are, however, other chlorination processes
available that small system operators should consider.
One such alternative that has been evaluated exten
sively by EPA’s WSWRD is the on-site salt brine
electrolysis chlorine generator system. The salt brine
solution together with the electrolytic cell generates a
solution (liquor) of primarily sodium hypochlorous
(chlorine) acid. Operators should be aware that some
vendors claim that their electrolytic generator
enhances pathogen (Cryptosporidium sp. and Giardia
sp.) inactivation by using the combined actions of
various mixed oxidant reactions generated from the
electrolytic cell. The further claim is that this mix of
oxidants minimizes DBP formation. However, EPA
has not been able to demonstrate the presence of any
other oxidant (other than sodium hypochlorous acid)
generated from these units.
Breakpoint Chlorination [9]
Small treatment operators should remember that
ground water, primarily in rural areas, tends to be
seasonally contaminated with ammonia nitrogen
from sources that may include crop fertilizers.
Because of this, they must achieve a stable residual
of stronger disinfectant-free chlorine. In other
words, the formation of chloramines must be
avoided by practicing “breakpoint chlorination.”
Breakpoint chlorination is the process in which
chlorine is added at levels that result in the oxida
tion (removal) of ammonia nitrogen. This happens
by converting the ammonia-nitrogen to nitrogen
gas in the presence of chlorine. The rate of
breakpoint chlorination is fastest at pH levels in the
range of 7 to 8, and tends to slow-down below and
above the optimum pH range. Thus monitoring and
controlling the pH is critical for optimization.
been practiced for nearly a century and was the early
method for industrial preparation of the chemical.
The basic operating principle involves electrolyzing a
concentrated brine solution which generates chlorine
at the anode and hydrogen together with sodium
hydroxide at the cathode. The hydrogen is allowed to
vent whereas the chlorine is allowed to remain in
contact with the electrolyte thus forming sodium
hypochlorite. Basically, the formation of sodium
hypochlorite occurs as follows:
Salt + Water + Energy => Sodium Hypochlorite +
Hydrogen Gas
Electrolysis of salt brine to produce hypochlorite has
On-site salt-brine electrolysis chlorine generator
systems can be very attractive to small operators,
because they are generally safer to handle and operate
than chlorine gas or liquid (sodium hypochlorite or
calcium hypochlorite) systems. EPA conducted studies
to evaluate three different on-site salt brine based
chlorine generators and compared them to each other
and to liquid bleach. EPA noted a wide variation in
prices when purchasing these units. The prices for the
three salt-brine generators designed specifically for
small systems cost in the range of $18,000 to $35,000
(depending on the manufacturer). Since most small
treatment system operators and facilities have a limited
budget, EPA decided to evaluate other avenues and
options for the small system operator. As a fourth
system, EPA purchased a salt-brine generator from a
swimming pool supply company for $750 and added
plumbing, pump, pressure gauge, flow control and
brine tank for $525 for a total equipment cost of
$1,275! (Figure 6-23)
When selecting an electrolytic chlorine generator,
operators should be aware that the performance of
each unit may be significantly affected by the quality
of the salt. Each vendor will recommend the type of
salt to be used in its unit. It is important to note that
all salt is not the same. Bromide levels in the salt can
significantly affect the level of bromate found in the
treated (chlorinated) water. Although safer than
conventional chlorine gas treatment, safety can also
be an issue with the chlorine salt brine generators. As
identified above, hydrogen gas is generated, and
although it is in very small amounts and for the most
part not considered hazardous, any collection of
hydrogen gas can be a potential for explosion or fire.
Thus, each electrolytic chlorine generating unit, or
the building in which it is set up, should have some
type of ventilation system to assure hydrogen gas
does not collect. It must be noted that the salt brine
electrolysis-based generators are generally safer to
handle and operate than conventional liquid or solid
sodium hypochlorite, calcium hypochlorite, or
chlorine gas systems.
31
Each utility or operator should evaluate the volume
and quality of salt being used to generate the required
amount of chlorine. Replacement parts and life for
items, such as electrolytic cell, static mixers, power
supplies and tubing and connectors, should be
considered. The operator should note that EPA has
demonstrated that drinking water disinfectants, such
as chlorine or monochloramine, at typical dosages
have virtually no effect on the inactivation of
Cryptosporidium oocysts. [21]
EPA conducted studies to evaluate three different onsite salt brine–based chlorine generators and com
pared them to each other and to liquid bleach (see
insert). Each unit was capable of generating sodium
hypochlorite on an as-needed basis by electrolyzing
salt water. Figures 6-23 through 6-25 show pictures
of the four on site chlorine generators evaluated.
Performance Evaluation of Various
Disinfection Technologies
For the on-site chlorine generators, the performance
can be evaluated based on the amount of chlorine
generated. The overall performance of the disinfec
tion system is based on the removal efficiency of
microbial organisms, such as Total Coliforms, Fecal
Coliforms, E. Coli, Cryptosporidium, etc. EPA
evaluated the performance of disinfection systems by
operating these systems under various “test” conditions.
Disinfection Summary
Each of the three chlorine generators evaluated
showed high concentrations (as much as 400 mg/L)
of free chlorine to be generated. A wide variety of
analytical methods were used to evaluate the disinfec
tant generation at the actual anode and cathode cells.
Based on the analytical results, EPA concluded that
only free chlorine was produced [22]. EPA studies
involving Cryptosporidium oocysts also did not show
any enhanced disinfection from using the electro
lyzed salt-brine “chlorine” solutions when compared
to liquid bleach “chlorine.” Cryptosporidium removal
efficiencies were less than 90%.
Ultraviolet (UV)/Ozone (O3)
EPA evaluated a packaged UV/O3 (also referred to as
Advanced Oxidation Process or AOP) system for
inactivating microorganisms. The unit evaluated was
capable of processing up to 10 gpm of water and is
engineered to ensure adequate UV intensity and
ozone residuals for advanced oxidation processes.
The UV/O3 system has a custom-built ozone genera
tion, injection and contacting system. The combined
system consists of a 13 gallon (49 liter) contact tank,
a 5 gram/hour ozone generator with air dryer, and a
cylindrical low-pressure 254 nm UV lamp reactor, and
a recirculation pump. The use of purity components,
32
Figure 6-23. On-Site Chlorine Generator #1.
Disinfection System Observations:
Research on on-site chlorine generators and UV/O3
treatment technologies have resulted in the following
observations:
The disinfection capabilities of disinfection systems
are a function of dosage and contact time. For the on-
site chlorine generators, the chlorine dosage and free
residual chlorine are critical performance parameters.
For UV/O3 treatment technologies, the UV intensity
and ozone dosage are critical performance parameters.
For both technologies, a reaction chamber or a contact
tank provides a mixing “area” for the disinfecting
agent(s) and microorganisms in the water.
On-site chlorine generators are designed to convert salt
to chlorine via an electrolytic cell. As a result, the
hazards associated with handling liquid chlorine are
not a concern. Salt is added to the chlorine generator
or contact tank in bulk and requires lifting by the
operator. Brine concentration levels are critical for
proper operation of on-site chlorine generators. The
accumulation of salt residue requires maintenance of
system tanks and piping.
UV/O3 systems oxidize organics instantly. Ozone
reacts quickly without leaving a residual disinfectant.
UV disinfection depends upon the intensity of the light
contacting the water. As a result, waters with low
turbidity and color are preferred for UV treatment.
Providing stable ozone dosage and UV intensity are
critical for providing consistent disinfection.
Several things can be done to improve UV/O3 system
performance. Air dryer dessicant can be replaced on a
regular basis to improve ozone generation. Ozone
dosage can be improved by increasing the air flow into
the ozone generator and optimizing the vacuum at the
venturi injector. For optimal performance, the UV/O3
system should be operated as specified by the manu
facturer. Alternatively, an oxygen generator can be
used to feed the ozone generator; this can be, however,
an expensive option.
such as a natural kynar venturi injector, a stainless steel
UV light housing, stainless steel recirculation loop
piping, and a rust proof extruded aluminum frame are
also features of this system. The total volume of the
UV/O3 system is 15 gallons (57 liters).
The combined UV/O3 system by far achieved the
highest disinfection rates for bacterial contamination.
The UV/O3 disinfection technology is useful in removing
other organic contaminants, such as MTBE, perchloroet
hylene, and trichloroethylene. Table 6-10 provides a
summary of the UV/O3 disinfection study evaluations.
As discussed before, EPA evaluated several types of
disinfection systems at the T&E Facility and various
field locations. The operating conditions, microbe
removal efficiency, and initial and operating cost for the
individual units vary widely. Table 6-9 presents a
summary of information for each type of disinfection
system. Note that the flow rates and the chlorine
generation rates, replacement part(s) cost(s), and
replacement frequency varies widely depending upon
the generator unit. The chlorine generation rate depends
upon the electrolytic cell size and the direct current
(DC) capacity of the system. Typically, the parts that
need to be replaced on an annual basis (depending upon
use) include: feed pump(s), electrolytic cell, and filters.
The replacement costs range between $100–$1,000
depending on the unit and the replacement part.
Advanced Oxidation Process for Disinfection &
Destruction
Advanced oxidation processes (AOP) use oxidants to
destroy organic contamination in drinking water.
Several different oxidants, such as ozone, hydrogen
peroxide, and hydroxyl radicals, may be used. EPA
evaluated the use of an AOP system comprised of
UV/O3 for disinfection potential and MTBE destruc
tion. This effort was intended to investigate if an
AOP system can be used to disinfect the water, and at
the same time destroy organic compounds.
AOP Using UV/Ozonation for MTBE Removal
Methyl-tert-Butyl-Ether (MTBE) is a gasoline
additive that has been found in drinking water. UV
irradiation and ozonation are known to effectively
destroy organic compounds in drinking water and
Table 6-10. Disinfection Summary Table (as tested)
Technology
Chlorine Generators
Cryptosporidium Removal
Flow Rate (gpm)a
Purchase Price
<90%
varies
$800 - 20,000
UV
99 - 99.9%
12
$2,000
Ozone
99 - 99.9%
12
$5,000
99.9 - 99.99%
12
$7,000
UV/Ozone
a
gpm = Gallons per minute
33
Chlorine exists in water in various forms. These
forms include free and combined chlorine and are
measures of the residual chlorine in the water supply.
[23]
Free Chlorine: Chlorine that is applied to water in its
liquid or gas form (hypochlorite) undergoes hydroly
sis (chlorine mixed with water) to form free (available) chlorine. This free chlorine is in the form of
aqueous molecular chlorine, hypochlorous acid, and
hypochlorite ion. The proportions of these free
chlorine forms are dependent on pH and temperature.
At the normal pH of most waters hypochlorous acid
and hypochlorite ion will predominate the solution.
Combined Chlorine: Free chlorine reacts easily with
ammonia and certain nitrogenous compounds to form
combined chlorine. Chlorine reacts with the ammonia
it forms chloramines. The chloramines are
monochloramine, dichloramine, and nitrogen trichlo
ride as well as some other chloro-derivatives. The
presence and concentrations of these combined forms
depend on pH, temperature, initial chlorine-tonitrogen ratio, absolute chlorine demand, and reaction
time. Note that both free and combined chlorine
maybe present at the same time and, historically, the
principal analytical problem has been to distinguish
between free and combined forms of chlorine.
Combined chlorine is determined by running free
chlorine and total chlorine tests and then subtracting
the free chlorine result from the total chlorine result.
Residual Chlorine: Residual chlorine is the amount
of chlorine remaining in the water after a specified
contact period.
other matrices. Thus, in addition to treatment for
Cryptosporidium, UV/O3 systems have also demon
strated the ability to treat MTBE in drinking water.
EPA has evaluated the removal of MTBE at influent
concentrations of 30 and 75 micrograms per liter (µg/
L) in a water supply. Ultraviolet light treatment alone
effected negligible MTBE removal. O3 alone was
capable of removing >80% of the MTBE after 60
minutes, but removal efficiency depended strongly on
the reaction time and on the initial MTBE concentra
tion. The combined UV/O3 process showed the best
potential for MTBE removal. Complete MTBE
removal was observed within 20 minutes reaction
time. Several by-products are generated as a result of
MTBE treatment. These by-products include t-butyl
alcohol (TBA), t-butyl formate (TBF), formaldehyde,
isopropyl alcohol, acetone, and acetic acid methyl
ester. [24] [25] Figures 6-26 and 6-27 demonstrate
the formation of byproducts and removal of MTBE in
the AOP process.
34
Figure 6-26. Package AOP Plant MTBE Removal vs Time,
30 µg/L Batch Test Run
Figure 6-27. Package AOP Plant Formation of t-BF vs Time
Injecting 30 µg/L MTBE.
7.0 Point-of-Use/Point-of-Entry Applications
Public water supply consumers may not always
possess the financial resources, technical ability, or
physical space to own and operate custom-built
treatment plants. Small drinking water treatment
systems, such as Point-Of-Use and Point-Of-Entry
(POU/POE) units, may be the best solution for
providing safe drinking water to individual homes,
businesses, apartment buildings, and even small
towns. These small system alternatives can be used
for not only treating some raw water problems, but
they are excellent for treating finished water that may
have degraded in distribution or storage or to ensure that
susceptible consumers, such as the very young, very old,
or immuno-compromised, receive safe drinking water.
For additional information, please see:
www.nsf.org/water.html
www.wqa.org
www.ndwc.wvu.edu
As discussed in Section 6, the 1996 SDWA Amend
ments identified two classes of technologies for Small
Systems: (1) compliance technologies and (2)
variance technologies. [11] A “compliance technol
ogy” may refer to a technology or any other technique
that is affordable by a small system that achieves
compliance with the MCL. These could include POU/
POE systems. “Variance technologies” are only
approved for those system sizes/source water quality
combinations when there is no available “compliance
technology.” So, if there is a “compliance technol
ogy” listed for your system, other “variance technolo
gies” will not be allowed. While “variance technolo
gies” might not reach the MCLs, they must achieve
the maximum removal or inactivation efficiency
affordable considering the size of your system and the
water quality of the source water. Public health must
be protected.
The 1996 SDWA require that the MCLs be set as
close as possible to the MCLGs as is “feasible.”
Feasible meant that the best technology or treatment
technique had to be determined based upon field
conditions, taking cost into account. The technolo
gies that meet this criterion are called “Best Available
Technology” (BAT). [10] Major concerns regarding
the use of POU/POE technology are:
–
the problem of monitoring treatment
performance so that it is comparable to central
treatment;
–
POU devices only treat water at an individual tap
(usually the kitchen faucet) and therefore raise
the possibility of potential exposure at other
faucets. Also, they do not treat contaminants
introduced by the shower (breathing) and skin
contact (bathing). Thus, POU/POE devices are
not designated as BAT;
–
these devices are generally not affordable by
large metropolitan water systems.
POU devices are only considered acceptable for use
as interim measures, such as a condition of obtaining
a variance or exemption to avoid unreasonable risks
to health before full compliance can be achieved. [26]
POE systems could be used if:
a.
The device is kept in working order. The PWS is
responsible for operating and maintaining all
parts of the treatment system although central
ownership is not necessary.
b.
An effective monitoring plan must be developed
and approved by the state before POE devices
are installed. A unique monitoring plan must be
installed that ensures that the POE device
provides health protection equivalent to central
water treatment.
c.
Because there are no generally accepted
standards for design and construction of POE
devices, and there are a variety of designs
available, the state may require adequate
certification of performance testing and field
testing. A rigorous engineering design and
review of each type of device is required. Either
the State, or a third party acceptable to the State,
can conduct a certification program.
d. A key factor in applying POE treatment is
maintaining the microbiological safety of treated
water. There is a tendency for POE devices to
increase bacterial concentrations in treated
water. This is a particular problem for activated
carbon technologies. Therefore, it may be
necessary to use frequent back-washing,
post-filter disinfection, and monitoring to ensure
the microbiological safety of the treated water.
The EPA considers this a necessary condition
because disinfection is not normally provided
after POE treatment, while it is commonly used
in central treatment.
e.
The EPA requires that every building connected
to a PWS have a POE device that is installed,
maintained, and adequately monitored. The
rights and responsibilities of the utility customer
must be transferred to the new owner with the
35
title when the building is sold (Federal Register,
1987).
In 1996, things changed. POU/POE could now be
considered a “Final Solution.” The 1996 regulations
required the POU/POE units to be “owned, controlled, and maintained by the PWS or by a person
under contract with the PWS operator to ensure
proper operation and maintenance and compliance
with the MCLs or treatment technique and equipped
with mechanical warnings to ensure that customers
are automatically notified of operational problems”
[10]. Under this rule, POE devices are considered an
acceptable means of compliance because POE can
provide water that meets MCLs at all points in the
home. It is also possible that POE devices may be
cost effective for small systems or NTNCWS. In
many cases, these devices are essentially the same as
central treatment. In 1998, POU devices were listed
as “compliance technologies” for inorganics, syn
thetic organic chemicals, and radionuclides, but not
for volatile organic chemicals (VOCs).
POU/POE Treatment
Currently, POU/POE treatment is used to control a
wide variety of contaminants in drinking water.
When evaluating various POU/POE treatment
systems, six major factors need to be considered in
the decision process. These factors are:
1.
quality and type of water source,
2.
type and extent of contamination,
3.
cost of water,
4.
treatment requirements,
5.
waste disposal requirements,
6.
state-approved operation and maintenance plan.
7-2 summarizes relative costs associated with various
POU/POE technologies. A major factor is whether
there is already in place a distribution system, versus
whether additional treatment must be installed in the
existing central system. Approximately 80% of the
total cost of any water utility is the installation and
maintenance of the distribution system. So in cases
where a distribution system would have to be installed to treat a contaminated drinking water source,
it may be more cost effective to install POU/POE
units. An example of this would be a community
where each home has a well and it was discovered
that the ground water was contaminated with a
pesticide, fertilizer, or chemical. Rather than install
miles of pipe, pumps, and storage facilities, a small
system could get state approval to install and main
tain units in each home. This might be economical
for upward of 100 homes depending on the cost of the
home units versus the amount and difficulty of
installing a distribution system and central treatment
facility. For those small systems that already have a
distribution system in place, the break-even point
would be for fewer home units (< 50). However, in
situations where the existing treatment plant could
not be economically or physically upgraded or if the
water quality is severely degraded while in the
distribution system, POU/POE may once again be a
Basically, the same technology used in treatment
plants for community water systems can be used in
POU/POE treatment. POU/POE treatment is applied
to reduce levels of organic contaminants, turbidity,
fluoride, iron, radium, chlorine, arsenic, nitrate,
ammonia, microorganisms including cysts, and many
other contaminants. Aesthetic parameters, such as
taste, odor, or color, can also be improved with POU/
POE treatment [26]. Table 7-1 summarizes key
features of commonly used POU/POE technologies.
Figure 7-1 shows a typical POU (under a kitchen
sink) RO Unit.
POU/POE Cost
The cost and application of POU/POE as a final
solution for a small system or portion of a larger
system is highly dependent upon the situation. Table
36
Figure 7-1. Typical RO Unit under a kitchen sink.
Table 7-1 Key Feature Summary of Commonly Used POU/POE Technologies [26]
Technology
Comments
Filtration
Filtration of water supplies is a highly effective public health practice. Microfiltration,
ultrafiltration, and reverse osmosis filtration systems have been shown to be
effective technologies for removing pathogens while being affordable for small
systems.
Activated Carbon
Activated Carbon is the most widely used POU/POE system for home water
treatment. Easy to install and maintain with low operating costs, usually limited to
filter replacement. Can remove most organic and some inorganic contaminants.
Membranes
Most POU membrane systems are reverse osmosis filters installed under the kitchen
sink, typically with either an activated carbon prefilter and an additional UV light
disinfection step to combat bacteria since the water is often stored under the sink
until used.
Ion Exchange
Commonly called water softeners when used for removing calcium and magnesium
from water. Other types of units remove anions, such as arsenic (arsenate),
hexavalent chromium, selenium (selenate), and sulfate.
Distillation
Distillation is most effective in removing inorganic compounds, such as metal (iron
and lead) and nitrates, hardness, and particulates, from contaminated water. Also
removes most pathogens. Can be effective in removing organic compounds
depending on the chemical characteristics of the compounds, such as water
solubility and boiling point. Distilling units have relatively high electrical demands
and require approximately 3 kilowatt-hours per gallon of water treated.
Air Stripping or Aeration
Aeration is a proven technology for removing volatile organic chemicals (for
example, dry cleaning fluid) from drinking water supplies for POE applications.
Aeration systems include: packed tower systems, diffused bubble aerators, multiple
tray aerators, spray aerators, and mechanical aerators. Storage, repumping, and
possibly disinfection facilities are needed after air stripping to distribute treated
water. Air stripping is typically used for POE applications where high concentrations
of volatile organics need to be removed from drinking water where carbon can be
used only for short periods of operation. Radon gas can also be removed by
aeration.
Modular Slow Sand Filtration
Slow sand filters housed in round fiberglass tanks (approx. 6 ft tall x 2.5 ft in
diameter) can treat 400-500 gallons daily. The systems are simple to operate and
have low capital (approx. $2,000) and operating costs. The unique feature of this
system is a very thin 1/8" thick filter blanket followed by a 1" thick polypropylene filter
blanket (similar to a furnace filter) to replace the biological mat that typically grows
on top of the sand (schmutzdecke). The blankets can simply be replaced when flow
is restricted without losing much sand or significant down-time.
Disinfection and Destruction
Disinfection is the most important consideration for POU/POE systems. Disinfectants
that are generally used in POU/POE systems are ultraviolet light, ozone, chlorine,
silver impregnated carbon, and iodine.
Chlorine - The most widely used water disinfectant. Can be used in the form of
liquid bleach, solid tablets, or generated onsite in portable generators.
Ultraviolet Light (UV) - Ultraviolet light is a popular home disinfection method in
combination with other treatment techniques. Does not add chemicals that can
cause secondary taste and odor problems. Units require little maintenance and
overdose is not a danger.
Ozone - Ozone has been used for disinfection, destruction, and precepitation of iron,
manganese, and some chemical contaminants. Ozone has to be generated and used
on-site as needed.
Iodine - Iodine has been used as an alternative disinfectant to chlorine because it is
easier to maintain a residual. However, iodine will not remove iron or manganese,
nor will it treat for taste and odors.
37
Table 7-2. Summary of Treatment Technologies and Costs [12]
Technology
Contaminants Removed
Operating Costs
Operation and
Maintenance Skills
Chlorine, Iodine
Microbial
Low
Low
Low
UV, Ozone
Microbial
Moderate
Low
Moderate
Sub-Micron Cartridge
Filtration
Protozoa, Bacteria
Low
Low to Moderate
Low
Reverse Osmosis
Microbial, inorganic chemicals,
metals, radium, minerals, some
organic chemicals
Moderate
High
High
Activated Carbon
Organic Chemicals, radon, odors
(solid block can filter protozoa, and
some bacteria)
Moderate
Moderate to High
Low
Packed Tower
Aeration
Radon, volatile organic chemicals,
tastes, odors
Moderate
Low
High
Ion Exchange
Inorganic chemicals, radium, nitrate
Moderate
Moderate to High
Moderate
Activated Alumina
Arsenic, Selenium, fluoride
High
High
High
Low Cost: $0 to $100
Moderate Cost: $100 to $1,000
practical alternative. [27]
Reverse Osmosis (RO) Home
Membrane Systems Field Study
The experiences presented below are from a field
study (in Virginia) focusing on removing naturally
occurring fluoride at the tap by using a POU system.
[28] The water being supplied to the homes was
provided by a well located within the local subdivi
sion. However, the driving force in the ultimate
acceptance by the Commonwealth of Virginia was the
POU treatment device’s ability to provide finished
water with acceptable levels of heterotrophic plate
count (HPC). A public-private partnership between
Virginia, EPA, and three POU vendors demonstrated
the use of RO systems to reduce fluoride for this
subdivision. This was a lower cost alternative to
abandoning the well and installing a large transmission
line to connect with a PWS several miles away.
Prior to this project, no treatment existed at the
subdivision’s well. The RO POU devices were
designed to treat only the water used for drinking and
cooking, and in some homes, the ice-making units in
refrigerators. The devices consisted of a sediment
prefilter, a high-flow, thin film (HFTF) RO mem
brane, a storage tank, and an activated carbon post
filter. Basic parameters, such as conductivity,
fluoride, HPC, total coliform, chlorine residual, pH,
sodium, total dissolved solids (TDS) and turbidity, were
used to evaluate the performance of the RO units.
Fluoride reduction was easily achieved for the entire
38
Initial Cost
High Cost: >$1,000
duration of the study, maintaining levels below the
secondary maximum contaminant level (SMCL) of
2.0 mg/L. However, HPC counts were elevated and
the decision was made to centrally chlorinate at the
well and replace the HFTF membranes with chlorineresistant cellulose triacetate (CTA) membranes and
remove the activated carbon post-filter. Subsequent
sampling demonstrated satisfactory fluoride and HPC
levels. Variances in fluoride and HPC concentrations
from site to site was explained by membrane degrada
tion and water use. The life expectancy of the
membrane depends on the environmental conditions.
High temperatures, bacteria, and high pH have an
adverse affect on the membrane life and result in poor
performance. Membranes were replaced when the
conductivity reduction decreased to 70% of the
influent. It was observed that conductivity reduction
was generally lower than fluoride rejection, so this
became a convenient, inexpensive, and conservative
means of monitoring system efficacy. A correlation
between HPC and chlorine residual was also ob
served. In fact, much of the project focused on
maintaining HPC levels below 500 cfu/mL.
Water quality sampling data indicated that the risk of
exceeding 500 cfu/mL at the tap was inversely
proportional to the chlorine residual in the post-RO
holding tank located under the kitchen sink. Any
time the residual exceeded 0.5 mg/L free chlorine, the
HPC limit was maintained, without exception. This
is extremely relevant, because an RO membrane
allows some chlorine to pass through, thus maintain
ing a residual at the tap. In this case, the water
reaching each household typically exhibited chlorine
residuals of 1 to 1.5 mg/L. Concentrations in the
holding tank between 0.5 and 1 mg/L were observed
frequently, indicating 33 to 50% passage of chlorine
through the membrane. This concentration decreases
over time in the finished water holding tank as it is
consumed through various oxidation reactions.
Because of this, it can be presumed that negligible
chlorine residuals indicate the unit has not been used
recently.
It was concluded that the HPC concern can be
eliminated by using chlorine-tolerant membranes and
by continually chlorinating the subdivision’s well. In
most cases, the RO storage tank unit was continually
refilled with chlorinated water. The HPC depended
on the chlorine residual in the storage tank, and
usually the residual chlorine remained high enough to
keep the unit clean. However, if the units were not
used daily, stagnant water in the tank caused a loss of
residual chlorine, and the water was susceptible to
microbiological growth. Researchers found that one
way to overcome this was to flush the tank daily.
This concept was demonstrated at a business site
during the study where the water was only used
sporadically.
Public Acceptance
At least 1 gallon per day (gpd) of RO water was
consumed by 77% of the homeowners, corresponding
to the 75% who used the system for all of their
drinking and cooking needs. Just 6% of participants
claimed to rarely use the RO water. Although
demonstrating fluoride reduction with RO has been
done before, the challenge in this study was maintain
ing microbiological integrity and gaining public and
regulatory acceptance for POU treatment. This
required an entirely different relationship between the
state authorities and the customers. The initial and
exit surveys confirmed not only public acceptance,
but showed an increase in customer satisfaction with
the POU treatment. When asked to rate the water
quality on a scale of 1–4, 52% of participants in the
initial survey rated the well water (not chlorinated)
quality as “fair” or “poor,” while 77% rated the RO
water as “good” or “very good” shortly after installa
tion. In the exit survey one year later, 94% rated the
RO water as good or very good, showing a significant
increase in the acceptance of the POU systems. This
acceptance may be due, in part, to the treated RO
water also being softer than the raw water.
The average RO water quality was rated 1.5 points
higher than the average tap water quality. The
average rating was calculated by summing the
individual ratings and dividing by the number of
responses. In the exit survey, RO water quality
averaged 3.5 points on a scale of 1–4, while well
water quality averaged 2.1 points. Moreover, RO
water quality was always rated at least as high or
higher than the well water quality, even when the
non-chlorinated well water was compared to chlori
nated RO water. This is noteworthy because the
switch to a chlorinated supply initially precipitated a
number of negative comments about taste. Microbio
logical integrity was not an issue for consumers
whereas it was the primary driver from the state
perspective.
Documentation of the increasing contamination of
U.S. ground water supplies grows almost daily.
Small water systems have been, and will continue to
be, the most vulnerable and the least capable of
meeting current and future drinking water regula
tions. But, competitive options and alternatives are
available in terms of drinking water treatment
technology. Central treatment can no longer be
thought of as the only solution, nor can it be thought
of as temporary or for aesthetics only.
AOP POE for PCE and TCE Removal, Vernon, CT
Most ozone whole-house POE applications for
drinking water in the past have been used for oxida
tion of inorganic contaminants, such as iron and
manganese. Recent projects have focused on the use
of ozone in conjunction with ultraviolet light and
granular activated carbon (GAC) for the destruction
of synthetic organic contaminants in groundwater and
disinfection of surface water supplies.
Two shallow drinking water wells in Vernon, CT,
were found to have elevated perchloroethylene (PCE)
and trichloroethylene (TCE) concentrations. As a
pilot project, a system comprised of a small AOP was
installed on one of these wells and provided up to 10
gallons per minute. The unit successfully served three
homes essentially as a packaged central treatment
system, although it was originally designed as a home
POE unit.
The AOP system consisted of an ozonator, an UV
light chamber, two GAC tanks, two treated water
storage tanks, a water meter, and an electric meter.
Water from the well was sent into the ozonation
chamber where ozone was fed into the water by a
venturi. A venturi forces a gas into a liquid (such as
ozone into water). The ozonated water then entered
the UV light chamber and then a contact tank where
the water was mixed for 3.5 minutes to achieve 100%
ozone saturation. The treated water then entered the
two GAC units where any residual ozone is converted
to oxygen, and any remaining contaminants are
removed. The treated water was then stored in the two
storage tanks and then distributed to the three houses
via the water meter.
The AOP system was tested over a two-month period,
and it treated more than 15,500 gallons of water. The
test results show an 80–90% reduction in PCE
39
concentrations following UV/O3 (with an influent
concentration between 250 and 663 µg/L). The PCE
concentrations following the GAC units were nondetectable. The capital cost of the system was
estimated to be approximately $6,000 (in 1991
dollars) with a maintenance cost of approximately
$150 per year. This amount includes electricity cost
and GAC replacement costs.
Ozone POE, Spruce Lodge, ME
Figure 7-2 shows the POE unit installed in the cellar
of a sportsman’s camp in Spruce Lodge, Maine, that
served up to 30 hunters and fishermen daily in a
lodge and four cabins. The raw water is filtered
through garnet followed by ozone injection (0.4 mg/L)
and then passes by a UV light to a holding tank.
The lake’s raw water quality was good. Finished and
distributed water was negative for total coliform.
HPC values varied somewhat with one episode
exceeding 500 cfu/mL. The variability could have
been the result of biofilm in the plumbing leading to
one of the cabins. The cabin had not been occupied
for days prior to sampling, thus resulting in old
stagnant water in the plumbing system’s service lines.
Ozonation byproducts for the treated water were
analyzed during this brief study and indicated lower
levels of all but one of the DBPs found in the raw
water. This could have been the result of the overall
good quality of the raw water and lack of ozonedemanding compounds, allowing reduction of the byproducts already formed in the raw water.
Low-humidity oxygen is required to produce ozone.
This POE unit used silica gel to remove moisture
from the air in the cellar rather than install an
expensive oxygen generator. Operational concerns
centered on the frequency of reconditioning the airdrying material. Because of the high humidity in the
cellar of the Lodge, the silica gel had to be recondi
tioned every few days. Although not expensive or
time consuming (30 minutes in an oven at 325oC),
constant attention to this might not be maintained in a
household and hence affect ozone generation and
disinfection efficiency. [26]
40
Figure 7-2. AOP POE unit installed in a cellar.
8.0 Remote Monitoring/Control
Many alternative treatment systems/technologies can
be equipped with up-to-date and modern sensor and
operating devices that can be monitored from remote
locations. This fact led EPA to consider remote
monitoring and control technology to improve
monitoring/reporting and reduce operation and
maintenance (O&M) costs. Although such telemetry
equipment could double the purchase cost of a
package plant, payback can be quickly realized
through reduced chemical use, low residue generation
(disposal), and increased reliability. Also, the cost of
subsequently networking multiple package plant sites
or water quality monitoring devices also decreases
after the initial cost for the telemetry equipment. It
has been demonstrated that various technologies are
being appropriately designed for small systems.
These will ultimately produce a better quality of
drinking water, accommodate the resources of small
systems, increase the confidence level of the cus
tomer, operator and regulator, and comply with the
monitoring and reporting guidelines. This section
will discuss the “lessons learned” in the use of remote
monitoring and control for treatment systems.
Small systems did not always use Remote Telemetry
Systems (RTS - a.k.a. Supervisory Control and Data
Acquisition [SCADA]) to their fullest potential due to
complex operating systems and controls that usually
required specially trained computer programmers or
technicians and costly service agreements. In the last
few years, RTS vendors have changed the way they
design and fabricate their systems, thus making them
more accessible to small drinking water treatment
operators.
The application of RTS to operate, monitor, and
control small systems from a central location (an
electronic “circuit rider”) is believed to be one mecha
nism that can reduce both MCL and M/R violations.
Through the application of RTS, the EPA has demon
strated that filters can be operated more efficiently for
particle removal, disinfectant doses altered in realtime in response to varying raw water conditions, and
routine maintenance and chemical resupply sched
uled more efficiently. Small independent systems can
contract with an off-site O&M firm or join with other
small system communities or utilities to either work
out schedules to monitor via telemetry or hire an
O&M services provider, while maintaining ownership. This type of approach would provide the small
system with the economies-of-scale medium and
larger systems have in purchasing supplies, equip
ment, and power, while also possibly receiving a
better trained operator.
The following factors must be considered before
purchasing a RTS:
■
Does the water treatment system justify the
requirement for a remote RTS system (is it
remotely located)?
■
Is the treatment system amenable (can water
quality instrumentation and operational
controls “send and receive” data in real-time)
to automation?
■
What types of communication media can be
used (phone, radio, cellular, etc.)? See Figure
8-1
■
How much automation and control is available
on the treatment system?
■
What type of RTS system is needed? Is the
goal to monitor, control, or both?
■
How many parameters are going to be
monitored and/or controlled?
■
Are there any specific regulatory monitoring
and reporting requirements?
[32]
EPA has been evaluating a variety of “small” RTSs
that allow a single qualified/certified operator to
monitor and control the operation of several small
treatment systems from a central location. Using
RTS results in optimum utilization of time for onsite
inspections and maintenance, thus allowing the
operator to visit only the problematic systems/sites
and better schedule the maintenance of these systems.
The expected results from an appropriately designed
and successfully deployed RTS are [31]:
■
enhanced water quality,
■
regulatory compliance, and
■
reduced cost for small communities
RTS Selection and Implementation
It is important to understand the treatment system
operation, location, and other environmental factors
when engineering and designing a RTS for remote
operation and maintenance.
The above factors will determine the need and the
basic design of the RTS system. These factors will
also help to determine if the system will complement
the needs of the treatment system and the utility
services. The cost of retrofitting a treatment system
for remote operations can be prohibitive. Many small
41
Table 8-1. Amenability of RTS to Treatment Technologies
Used for Small Water Systems [32]
data that can be used to significantly enhance
treatment system operation and reduce system
downtime. The overall benefits include:
Amenability for
Automation/Remote
Monitoring & Control*
•
Improved customer satisfaction, improved
consumer relations and, other health benefits.
Air Stripping
Oxidation/Filtration
Ion Exchange
Activated Alumina
4-5
1-2
3-4
1-2
•
Satisfies regulatory recordkeeping and reporting
requirements.
•
Reduces labor costs (associated with time and
travel) for small system operators.
Coagulation/Filtration
Dissolved Air Flotation
Diatomaceous Earth Filtration
Slow Sand Filtration
Bag and Cartridge Filtration
1-2
1-2
3-4
3-4
3-4
•
Provides the capability to instantly alert
operators of undesirable water quality and/or
other changes in treatment system(s).
Disinfection
Corrosion Control
Membrane Filtration Systems
Reverse Osmosis/Nanofiltration
Electrodialysis Systems
Adsorption
Lime Softening
4-5
3-4
3-4
4-5
4-5
3-4
1-2
•
Troubleshooting can be performed remotely,
reducing downtime and increasing repair
efficiency.
•
Fully automated treatment systems can identify
monitored parameter trends and adjust operating
parameters accordingly.
•
Provides an attractive alternative to fixed
sampling and operation and maintenance
schedules.
Technology
*A rating scale of one to five (1 to 5) is employed with one (1) being
unacceptable or poor and five (5) being superior or acceptable.
treatment systems currently in use were not originally
designed for remote operations. Rural areas have
little or no electronic hardware to communicate with
a telemetry system. Thus, the cost of upgrading a
treatment system for remote operations can be
significant. It is essential that the treatment system
be fairly amenable to automation. Table 8-1 identifies
the current amenability of small package plant
treatment technologies to remote telemetry.
Many of these treatment technologies are available as
package plants with some degree of automation
designed specifically for small systems. The mem
brane technologies are extremely amenable to
automation and remote control and also provide
efficient removal for a wide range of drinking water
contaminants.
Federal regulations require all small PWS operators
to monitor to assure the quality of the treatment
processes. Constant remote monitoring of the water
quality has provided substantial savings in time and
travel cost for O&M. It has been determined that
remote telemetry can support regulatory reporting
guidelines by providing real-time continuous moni
toring of the water quality and reporting the informa
tion electronically. However, due to concerns of
assuring the best water quality to the consumer, many
state regulators resist accepting the remote monitor
ing guidelines. Table 8-2 presents a range of costs
for RTS system components.
Long-term real-time remote monitoring can provide
42
A real world example of a small system equipped
with remote monitoring and control is included in
Section 9.0 of this document.
Table 8-2. Cost Estimates of SCADA System
Components [32]
SCADA System
Component
Component Option
Range of Costs
Hardware
Main Computer
SCADA Unit
$1,000 - 3,500
500 - 30,000
Software
Operating System
Telemetry System
Data Collection & Loggers
$250 - 750a
500 - 30,000b
250 - 8,000
Communication Telephone
Medium
Cellular
Radio
Satellite
Instrumentation Valves
Switch
Sensor
$75 - 125c
250 - 500d
1,500 - 3,500e
20,000 - 75,000f
$25 - 1,500g
25 - 300g
350 - 85,000h
Operating system software is usually included in the purchase price of a computer.
SCADA software is usually included in the purchase price of the hardware.
c
Monthly service charges are estimated.
d
Activation, roaming, and monthly service are estimated and included.
e
Transmission cost of Integrated phone, cellular, radio frequency, and satellite
system.
f
Satellite systems cost for transmissions, monthly service and activation charges are
estimated
g
Cost per valve and/or switch.
h
Cost per individual sensor or sensor system.
a
b
Remote
Location
Communication
Media
Central
Office
Satellite
OR
Cellular Network
OR
Radio (RF) Communication
OR
Telephone Line
OR
Direct Wire
Figure 8-1. Possible layout(s) of a Remote Telemetry System.
43
44
9.0
A Real World Packaged Solution
In May 1991, EPA provided funding to support a
research project titled “Alternative Low Maintenance
Technologies for Small Water Systems in Rural
Communities.” This project involved the installation
of a small drinking water treatment package plant in a
rural location in West Virginia. The primary objective
of this research was to evaluate the cost-effectiveness
of membrane package plant technology in removing
microbiological contaminants. The secondary
objective of this project was to automate the system
and minimize O&M costs.
The EPA test site is located in rural McDowell
County, West Virginia. The treatment system is
located approximately 12 miles from the McDowell
County Public Services Division (MCPSD) office
through Appalachian Mountain terrain. Figure 9-1
shows the town MCPSD services. The water source
is an abandoned coal mine. The raw water quality
parameters are shown in Table 9-1. Prior to 1994, an
aerator combined with a slow sand filter was used to
treat water at this site (see Figure 9-2). This com
bined unit had been operational for over 60 years and
needed substantial repairs. Water flowed by gravity
from the abandoned coal mine to the aeration trays
built over a six-foot diameter slow sand filter. A
hypochlorinator disinfected the filtered water, which
then flowed by gravity through the distribution
system to the consumer. The volume of water from
the mine was sufficient for the small rural community
of approximately 100 people.
Table 9-1. Raw Water Quality and
Contaminant Specifications
Total Coliform
1,150 CFU/100
Fecal Coliform
650 CFU/100
Hetrotrophic Plate Count (PCA)
900 CFU/mL
Hetrotrophic Plate Count (R2A)
37,000 CFU/mL
Fecal Streptococci
520 CFU/mL
Escherichia coli
100 CFU/ml
TOX
8.2 ug/L
Total Hardness (CaCO3)
180 mg/L
Specific Conductivity (micromhos)
350 micromhos
Ca
60 mg/L
Mg
9 mg/L
Na
4 mg/L
SO4
12 mg/L
NO3
1 mg/L
greater than 4.0 mg/l as received by the consumer.
Consumers were being charged $20 per month for
water that distinctly tasted and smelled like chlorine.
An engineering study conducted by MCPSD esti
mated the cost of a new conventional water treatment
system (to replace the existing treatment system and
distribution system) to be $328,000, resulting in a
cost of $10,933 per customer. Consumers considered
this an impractical and unacceptable solution. It was
essential that the replacement technology operate in a
rugged environment with minimal maintenance.
Also, the treated water quality characteristics were
Figure 9-1. McDowell County.
The system had several problems. The filtration was
not very effective, and the operator used excess
chlorine for disinfection. The water quality tests
indicated that the residual chlorine content was
Figure 9-2. Old treatment system.
45
required to be consistent with the SWTR and the
Total Coliform Rule as described below [11]:
•
No more than one sample per month may be
total coliform positive,
•
HPC must be < 500 mL if the chlorine residual
value is < 0.2 mg/L
•
Turbidity of the treated water must at all times
be <5NTU and normally can not be >0.5NTU
Thus, the EPA and MCPSD investigated various
alternative economically feasible technologies. Based
on a review of available technologies, the EPA
determined that a packaged UF system would be
ideally suited for this location. In 1992, a packaged
UF water treatment system was purchased and
installed at this site.
Figure 9-3. Packaged UF System.
Test Site Treatment Technology Overview—
Packaged UF System
The packaged UF system has an overall dimension of
12'10"L x 7'H x 3'W with an approximate empty
weight of 800 pounds (see Figure 9-3). The picture
shows the front view of the system as purchased and
installed in 1992. The main system components of
the UF system are as follows:
•
Three 8" x 40" spiral-wound UF membrane
cartridge elements arranged in series and
contained in a fiberglass vessel. The UF
elements are polymeric spiral-wound type with a
nominal MWCO of 10,000.
•
The package UF system includes a control panel,
feed pumps, recirculation pumps, 10–25-micron
bag pre-filter, 30 gallon cleaning tank, a chlorine
monitor, electrically actuated control valves,
temperature and pressure gauges, and sight
rotometers
•
The unit is interconnected with Schedule 80
polyvinyl chloride (PVC) piping. The UF
system is designed to produce 10,000 gallons per
day (GPD) treated drinking water.
The packaged UF system was installed on a new
cement slab and the community constructed a 12' by
24' cinder block building to secure and protect the UF
system (see Figure 9-4).
Overview of Remote Monitoring and Control
Technology Installed at the Test Site
The packaged UF system as initially installed used a
manufacturer provided programmable logic controller
(PLC), along with PLC controllable hardware for
automation. The UF system also included several
instruments and sensors, such as an online pH sensor,
online chlorine sensor, pressure gauges, etc. The UF
46
Figure 9-4. New cinder block building.
system operating and water quality parameters were
manually logged and recorded from the instrument’s
analog/digital displays. In 1996, the EPA developed,
installed, and tested a RTS at the site. The RTS used
commercially available hardware. The RTS software
was a MSDOS-based system that was hardware
specific, not very user-friendly, and the overall cost of
ownership was not practical. Thus, the system
operated with proprietary, EPA-developed software.
In 1998, the EPA updated the RTS unit with a
commercially available, off-the-shelf, user-friendly,
Microsoft® Windows®-based RTS. Figures 9-5 and 96 present two operator computer screen shots. The
RTS selected was fairly inexpensive, smart, userfriendly and scaleable. The capital cost for the
hardware and instrumentation was approximately
$12,000, and the total cost (including technical
support, training, and set-up) was about $33,000.
The EPA worked with MCPSD to remotely monitor
the UF system for water quality. The RTS is also
being evaluated for its effectiveness in fulfilling the
regulatory monitoring and reporting requirements,
and its effectiveness in reducing the manpower
operating parameters without operator intervention
makes the system “smart.” This system can also be
programmed to dial-out and page the operator during
“alarm” conditions. The existing package plant was
upgraded and modified as necessary to accommodate
RTS functionality. MCPSD currently operates and
maintains this system. The RTS has operated trouble
free since installation. Based on the initial success,
EPA has recently installed similar units at two other
locations within McDowell County.
Figure 9-5. Welcome screen.
Figure 9-6. System summary (note the high chlorine alarm).
requirements during the operation and maintenance
of the UF system.
This RTS can be remotely programmed to optimize
treatment system operation based on observed trends.
For example, if the monitored trends indicate that
during a certain period the storage tank water levels
are lower than normally observed during that time,
the system can be programmed to automatically
increase the water supply to the storage tank. This
type of trend-based adjustment can potentially
eliminate water supply disruptions. This ability of the
RTS unit to adjust treatment and distribution system
The remote monitoring and control system proved
to be a useful tool for troubleshooting. Specifi
cally, MCPSD was able to monitor and download
activity logs of the system and monitor system
performance over time. This enabled MCPSD
personnel to schedule maintenance activities based
on observed pressure data. The system also
helped MCPSD to monitor the system operation
remotely during inclement weather conditions.
47
48
10.0
Funding and Technical Resources
Most federally funded water projects are financed by
the EPA’s Drinking Water State Revolving Fund
(DWSRF) and/or the U.S. Department of
Agriculture’s Rural Utilities Service (RUS) [33].
There are also various foundations, bank programs,
state programs, other federal programs, and professional
organizations that provide grant and loan assistance.
This section briefly describes each of these resources.
EPA Drinking Water State
Revolving Fund (DWSRF)
EPA is aware that the Nation’s water systems must
make significant investments to install, upgrade, or
replace infrastructure to continue providing safe
drinking water to their 250 million customers.
Installing new treatment facilities can improve the
quality of drinking water and better protect public
health. Improvements are also needed to help those
water systems experiencing a threat of contamination
due to aging infrastructure systems. In order to
improve small drinking water systems and further the
health protection objectives of the SDWA amend
ments, EPA entered into agreements with “eligible”
states to make capitalization grants available through
the state programs. The 1996 SDWA Amendments
established the DWSRF to make funds available to
PWSs to finance infrastructure improvements. The
program also emphasizes providing funds to small
and disadvantaged communities and to programs that
encourage pollution prevention as a tool for ensuring
safe drinking water. Section 11.0 of this document
identifies the various state agencies and their web
locations.
To Find Out More About DWSRF:
www.epa.gov/safewater/dwsrf.html
Capacity development refers to the technical,
financial, and managerial capability needed to
consistently achieve the public health protection
objectives of the Safe Drinking Water Act (SDWA).
A key component of the 1996 SDWA Amendments,
capacity development ties into the Drinking Water
State Revolving Fund (DWSRF) in two important
ways. First, states may set aside funds from their
DWSRF allotments to develop and implement
capacity development programs. Second, the EPA
is required to withhold DWSRF funds from states
that fail to implement capacity development
provisions.
basis, according to State-determined
affordability criteria.
In order to qualify for DWSRF funds, states must
have an EPA-approved capacity development program and an operator certification program. Funds
can be used for loans, loan guarantees, and as a
source of reserve and security for other (leveraged)
funds. States must also contribute an amount equal to
20% of the total federal contribution. As loans are
paid back, the State can re-loan the money to other
systems, thus the term “revolving” in DWSRF. Any
system that gets a loan must demonstrate that it has
the technical, financial, and managerial capacity
(“capacity development program”) to operate its
system for the long-term.
Since 1997, Congress has authorized $9.6 billion for
the 50 states and Puerto Rico. Currently, the indi
vidual State grants range from $7 million to $80
million per year. Loans can have interest rates
Eligible project categories for DWSRF include:
The DWSRF program required that States develop a
priority system for funding infrastructure projects
based on three criteria established by the SDWA
Amendments. States are also required to solicit and
consider public comment when developing their
priority systems. Projects are ranked and funding is
offered to the highest ranked projects that are ready to
proceed. Priority goes to those eligible projects that:
■
address the most serious risk to human health;
■ are necessary to ensure compliance with the
requirements of the SDWA Amendments; and,
■
assist systems most in need, on a per household
Treatment – Projects designed to maintain compli
ance with regulations for contaminants causing
health problems.
Transmission and Distribution – Projects related to
installing or replacing pipes.
Source – Projects that rehabilitate wells or develop
new water sources to replace contaminated sources.
Consolidation – Projects that combine sources or
systems if one is unable to maintain technical,
financial, or managerial capability.
Creation of New Systems – Projects that establish
new systems or projects involving consolidation of
multiple systems that have severe problems.
49
For a state to be “eligible” for DWSRF, it needs
to have an EPA-approved operator certification
program. Each state has different needs and so
programs vary state-to-state. Training and
certification program ensures drinking water
operator competency, and therefore protects
public health. In almost all states, some training
is provided by the Rural Water Association and/or
the local chapter of AWWA. These classes are
generally free or very low cost. But, sometimes
small systems simply can’t provide the money to
cover an operator’s travel or lodging costs, even if
the tuition is free. EPA has initiated a grant
program that will make money available to cover
certain training and certification expenses.
As required by SDWA, EPA must reimburse the
costs of training for people operating community
and nontransient noncommunity public water
systems serving 3,300 persons or fewer that are
required to undergo training. The reimbursement
is to be provided through grants to states. EPA
will determine the total amount that each state is
to receive to cover the reasonable costs for
training and certification for all such operators.
Funding assumptions include money to cover a
per diem for unsalaried operators, tuition costs for
training classes, fees for initial certification
renewal, and mileage. States may apply for and
receive the expense reimbursement grant funds
once their operator certification program has
received EPA approval to apply for and receive its
expense reimbursement grant. As part of the
grant application, states must submit a work plan
and annual progress report outlining how these
funds are to be used.
Several financing options are available for
communities that seek DWSRF funding, including:
Low-Interest Loans—Loan rates range between
zero percent and the current market rate, with a 20year repayment period.
Refinance or Purchase Local Debt—Helps to
reduce a community’s cost of borrowing.
Purchase Insurance or Guaranteed Local Debt—
Can improve credit market access or reduce
interest rates.
Leverage Program Assets—Through issuing bonds
to increase the amount of funds available for
projects.
Disadvantaged Assistance—Provides help by
taking an amount equal to 30 percent of a capitali
zation grant for loan subsidies or extending the
repayment period from 20 to up to 30 years.
50
between 0% and the market rate. Special help is
available for disadvantaged communities. DWSRF
guidelines require that at least 15% of the loan fund
be used for small PWSs.
U.S. Department of Agriculture
Rural Utilities Service (RUS) Loan
and Grant Program
The RUS and its predecessor, the Farmers Home
Administration, have provided more than $25 billion
in loans and grants since 1940. RUS has often been
described as the “funder-of-last-resort” for communi
ties that have nowhere else to turn. [29] The RUS
provides both loans and grants to rural communities
for drinking water, wastewater, solid waste, and storm
water drainage projects. These are administered
locally by state and district Rural Development
offices. RUS loans are designed especially for
communities unable to obtain money from other
sources at reasonable rates and terms. Funds may be
used to install, repair, improve, or expand rural water
facilities. Expenses for construction, land acquisi
tion, legal fees, engineering fees, interest, and project
contingencies can also be covered. The RUS interest
rates are set at three levels: the poverty line rate, the
intermediate rate, and the market rate, each of which
has specific qualification criteria.
State Rural Development offices can provide specific
The current interest rates (for the second
quarter of year 2001 that apply to all loans
issued from April 1 through June 30, 2001) are:
poverty line: 4.5 percent (unchanged from the
previous quarter);
intermediate: 4.75 percent (down 0.25 percent from
the previous quarter); and
market: 5.125 percent (down 0.375 percent from the
previous quarter).
information concerning RUS loan requirements and
application procedures. For the phone number of your
state Rural Development office, contact the National
Drinking Water Clearinghouse at (800) 624-8301 or
(304) 293-4191.
Other Financial Assistance
To Find Out More About RUS:
www.usda.gov/rus/water/states/usamap.htm
Programs
The following types of funding tools can also be used
to buy equipment. Each offers advantages and
disadvantages not only in eligibility and terms, but
also in the amount of time and information needed to
fill out the application forms.
Loan Programs
Commercial loans are available from banks or other
financial institutions and the application process can
be relatively quick, but the interest rates are generally
higher with less favorable pay-back rules. State
programs generally offer better rates and terms for
those systems that are ineligible for conventional
types of financing.
Grant Programs [34]
Grants, which are awarded to a state or local govern-
CoBank, a federally charted financial institution
owned and patronized by about 2,400 agricultural
cooperatives and rural utilities, provides one
popular type of loan program. As customers, these
cooperatives and utilities provide capital to the
bank by securing equity based on money borrowed.
Long-term and interim loans are available for
construction and equipment financing if applicants
meet the eligibility requirements. PWSs serving a
population of fewer than 20,000 that can show an
acceptable credit risk are generally eligible.
[34]
To Find Out More About CoBank:
www.cobank.com
ment or nonprofit organization, are sums of money
that do not have to be paid pack. They can be
awarded by the federal government (e.g., Community
Development Block Grants) to state or local govern
ments or by states to local governments. Applying
for grants, however, can require a significant commit
ment of time by utility personnel. In addition, the
availability and timing of the grant award may not
match the utilities’ needs. Most grant programs
possess limited funds, and competition for these
funds may forestall funding for many projects.
Grants also have project eligibility requirements, and
some programs may specify that the grantee provide
a share of the total project funds.
The Department of Housing and Urban Development
(HUD) provides grants to drinking water utilities
through the Community Development Block Grant
(CDBG) program. Applications must be filed
through the appropriate state government office;
states have the authority to administer the distribution
of the HUD funds. Grants are targeted to PWSs
serving low- and moderate-income households, and
drinking water treatment systems are among the types
of projects eligible for assistance. On average, the
grants cover 50 percent of project costs, although
areas experiencing severe economic distress are
eligible for grants that cover up to 80% of project
costs.
The Department of Commerce provides grants
through the Economic Development Administration’s
Public Works and Development Program. Applica
tions must be submitted to the state economic
development agency; states are authorized to admin
ister the funds. The drinking water project must be
located in a community or county determined to be
economically distressed, and the project must be
directly related to future economic development.
Some restrictions apply when grants are provided in
conjunction with other financial assistance. The
combined funding is limited to 80 percent of the total
project cost.
Qualifying applicants in designated Appalachian
Regions in 13 states can also apply to the Appala
chian Regional Commission (ARC) for grants in
conjunction with the Tennessee Valley Authority.
Local development districts provide assistance in
preparing an applicant’s proposal. Priority funding is
determined each year by the state governors, Appala
chian district personnel, and ARC members. All
projects that qualify for grant funding must be
directly related to economic development, housing
development, or downtown revitalization and im
provement. Drinking water treatment systems are
among the types of projects eligible for assistance.
One restriction of ARC grants is that they are limited
to 50% of project costs and require the recipients to
provide the other 50%. An exception is made for
economically distressed counties, which can receive
80% and must supply only 20%. In 1992, 90 counties
out of 398 in the Appalachian region fit within this
“distressed” category. However, to raise the remain
ing 20% of funds, owners of small systems in
distressed counties should aggressively seek other
innovative sources of funding.
The Indian Health Service (IHS), which is part of the
Department of Health and Human Services, provides
grants for projects undertaken by American Indians
and Alaska Natives. In 1959, Congress passed the
Indian Sanitation Facilities Act to provide improved
health conditions by improving sanitation, sewer,
solid waste, and drinking water facilities. To date,
more than $1 billion has been spent on the effort, and
more than 182,000 homes have received water, sewer,
51
and solid waste services for the first time. IHS grants
support health aspects rather than economic develop
ment or environmental preservation and do not
include funding for operation and maintenance. No
matching funds are necessary, and IHS grants can be
consolidated with those from other agencies.
No-interest loans
In 1989, the Rural Electrification Administration
(REA) implemented a program to promote projects
that “will result in a sustainable increase in the
productivity of economic resources in rural areas and
thereby lead to higher levels of income for rural
citizens.” This program is the Rural Economic
Development and Grant Program. The program
makes no-interest loans available for up to 10 years
and grants of as much as $100,000. The local REAs
act as sponsors for the actual project owners. Drink
ing water projects are eligible for these no-interest
loans.
Table 10-1 provides a summary of these funding
sources. Technical and administrative assistance for
applying for these funds can be obtained from various
agencies identified in Table 10-2.
Foundations
Private foundations are another possible source of
funding for small PWSs. A source of information
about foundations that provide grants, The Founda
tion Directory, provides basic descriptions of founda
tions that have $1 million or more in assets or that
annually award $100,000 or more. Information about
smaller foundations can be obtained from the local
Internal Revenue Service (IRS) office. The IRS
annually collects Form 990-PF (Return on Private
Foundations) from foundations of all sizes, and it
compiles information about the foundations’ inter
ests, restrictions, application procedures, and deadlines.
Information about foundations can also be obtained
from Source Book Profiles published by The Founda
tion Center, which contains information about the
Table 10-1. Federal Funding Programs for Small Public
Water Systems
Contact
Telephone
Appalachian Regional Commission (ARC)
(202) 884-7799
Department of Housing and Urban
Development (HUD) Community
Development Block Grants
(202) 708-2690
Economic Development Administration
(EDA)
(202) 482-5081
Indian Health Service (IHS)
(301) 443-1083
52
Table 10-2. Technical and Administrative Support for
Small Public Water Systems
Contact
Telephone
American Water Works Association
(303) 794-7711
ext. 6191
National Rural Water Association
(580) 252-0629
Rural Community Assistance Program
(202) 408-1273
Rural Electrification Administration (private;
provides some financial funding)
(202) 720-9540
Rural Information Center
(800) 633-7701
National Drinking Water Clearinghouse
(800) 624-8301
thousand largest foundations. Also, the Cooperative
Assistance Fund represents foundations that pool
their funds to make program-related investments
primarily for low-income urban and rural communi
ties. Table 10-3 lists a number of private foundations
providing backing to rural economic development
programs.
Technical Resources Environmental Technology
Verification (ETV), Drinking Water
Systems Center
ETV Program Overview
Historically, the EPA has evaluated technologies to
determine their effectiveness in preventing, controlling, and cleaning up pollution. To accelerate the use
of environmentally beneficial technologies, the EPA
established the Environmental Technology Verifica
tion (ETV) program to collect and disseminate
quality-assured data on the performance and opera
tion and maintenance issues of specific-model
commercial-ready environmental technologies.
Important Principles
The ETV program does not certify product conform
ance to a standard. There are no pass/fail criteria
associated with the ETV process. The ETV program
offers an opportunity for characterizing product
performance under a predetermined set of test
conditions. The ETV program offers flexibility to
participating manufacturers and vendors for technol
ogy evaluations as either short pre-screening studies
on narrowly defined water quality and operating
conditions or more comprehensive verification
evaluations over multiple seasons of testing and/or
multiple testing locations under varying conditions.
ETV testing results become public information.
Manufacturers involved in a product evaluation
Table 10-3. Foundation Backing Rural Economic Development Program
Foundation
Telephone
Support Available
Mary Reynolds Babcock
Foundation
(336) 748-9222
Grants include operating support for smaller organizations for
rural grassroots groups, primarily in North Carolina and the
Southeast.
Otto Bremer Foundation
(888) 291-1123
or
(651) 227-8036
Grants include some operating support for rural poverty
programs and support to strengthen the rural economy of
Minnesota, North Dakota, and northwestern Wisconsin.
Ford Foundation
(212) 573-5000
Grants for experimental programs about rural poverty that can
inform public opinion
W.K. Kellogg Foundation
(616) 968-1611
Grants for collaborative rural delivery of human services, rural
leadership development, and training local government officials
Charles Stewart Mott
Foundation
(810) 238-5652
Grants for startup capital and capacity building to create
economic opportunities for low-income people
Northwest Area Foundation
(651) 224-9635
Grants for rural development in Idaho, Iowa, Minnesota,
Montana, North Dakota, South Dakota, Washington, and Oregon
receive an ETV Verification Report and Verification
Statement (a 5- to 6-page summary document) that
describes their product and its performance results
based on the specified evaluation conditions.
Participation in the ETV program by manufacturers is
voluntary. However, ETV reports can be valuable
tools for vendors through dissemination of their
equipment’s performance results, and support toward
achieving regulatory and market place acceptance.
particulate material; reduce precursors to disinfection
by-products; reduce arsenic, nitrate, organic, and
inorganic chemicals; and radionuclides. The test
plans and protocols may be used by utilities, state
drinking water agencies, and others interested in
evaluating technologies. If the testing is coordinated
with NSF and its partners, the EPA and independent
ETV-qualified field testing organizations, the manu
facturer will receive ETV report documents present
ing the testing results.
Drinking Water Systems Center
On October 1, 2000, the EPA entered a joint venture
with NSF International to form the ETV Drinking
Water Systems (DWS) Center to provide independent
performance evaluations of treatment technologies
with the goal of raising awareness for new product
applications. The DWS Center efforts include
evaluation of a wide range of treatment products from
complete package systems to individual treatment
modules or components. Direction and prioritization
of ETV activities are provided by a stakeholder input/
feedback process. DWS Center stakeholders include
representatives from State and Federal regulatory
agencies, manufacturer-vendor groups, water utility
and technology-user organizations, and the scientificengineering-technology community.
ETV Outputs
The ETV DWS Center has conducted equipment
evaluations involving several types of technologies:
Test Plans and Protocols
The DWS Center has nine contaminant-specific
verification testing protocols and 23 technologyspecific test plans that outline testing procedure
requirements that must be followed in the specific
product evaluations. The contaminant-specific
protocols cover technologies that inactivate or
physically remove microbiological contaminants;
•
UV and ozone inactivation of microbiological
contaminants
•
Microfiltration and ultrafiltration membranes for
microbial control
•
Coagulation/filtration package systems for
arsenic and microbials
•
Nanofiltration membranes for DBP control
•
Reverse osmosis for arsenic removal
•
On-site sodium hypochlorite generation for
disinfection
•
Bag and cartridge filters for microbial control
•
Diatomaceous earth filter systems for microbial
control
Information about ETV activities, copies of ETV
reports, test plan/protocol documents, and mailing
lists may be obtained at the ETV web site,
www.epa.gov/etv/.
53
54
11.0 Additional Information Sources
For more information about small PWSs, funding resources, agency contacts, and other water system related
topics mentioned in this document, please contact the following agencies or groups for assistance:
Federal resources
Resource
Contact
Occupational Safety & Health Administration
Web Link: www.osha.gov
U.S. Army Corps of Engineers
Phone: (202) 761-0008
441 G. Street, NW
Washington, DC 20314
Web Link: www.usace.army.mil
U.S. Geological Survey
Phone: (888) 275-8747
Web Link: www.usgs.gov
U.S. Dept. of Agriculture
Rural Utilities Service
Phone: (202) 720-9583
1400 Independence Ave, SW
Web Link: www.rurdev.usda.gov/rus/index.html
U.S. Environmental Protection Agency (EPA)
Web Link: www.epa.gov
U.S. EPA Office of Groundwater and Drinking Water
Phone: (202) 260-5543
Ariel Rios Building
1200 Pennsylvania Avenue, NW
Web Link: www.epa.gov/OGWDW/
U.S. EPA Office of Research and Development
Web Link: www.epa.gov/ORD/
U.S. EPA OGWDW - Public Drinking Water Systems
Web Link: www.epa.gov/safewater/pws/pwss.html
U.S. EPA OGWDW - Small Systems
Web Link: www.epa.gov/safewater/smallsys.html
U.S. EPA Region 1 (includes: Connecticut, Maine,
Massachusetts, New Hampshire, Rhode Island,
Vermont)
Phone: (888) 372-7341 (617) 918-11111
Congress St., Suite 1100
Boston, MA 02114
Web Link: www.epa.gov/region01/
U.S. EPA Region 2 (includes: New Jersey, New York,
Puerto Rico, Virgin Islands)
Phone: (212) 637-3000
290 Broadway
New York, NY 10007
U.S. EPA Region 3 (includes: Delaware, Maryland,
Pennsylvania, Virginia, West Virginia, Washington DC)
Phone: (215) 814-5000
1650 Arch Street
Philadelphia, PA 19103
U.S. EPA Region 4 (includes: Alabama, Florida,
Georgia, Kentucky, Mississippi, North Carolina, South
Carolina, Tennessee)
Phone: (404) 562-9900
61 Forsyth Street, SW
Atlanta, GA 30303
U.S. EPA Region 5 (includes: Illinois, Indiana,
Michigan, Minnesota, Ohio, Wisconsin)
Phone: (312) 353-2000
77 West Jackson Blvd.
Chicago, IL 60604
U.S. EPA Region 6 (includes: Arkansas, Louisiana,
New Mexico, Oklahoma, Texas)
Phone: (214) 665-6444
Fountain Place 12th Floor, Suite 1200
1445 Ross Avenue
Dallas, TX 75202
U.S. EPA Region 7 (includes: Iowa, Kansas, Missouri,
Nebraska)
Phone: (913) 551-7000
726 Minnesota Avenue
Kansas City, KS 66101
55
Resource
Contact
U.S. EPA Region 8 (includes: Colorado, Montana,
North Dakota, South Dakota, Utah, Wyoming)
Phone: (303) 312-6312
999-18th St., Suite 300
Denver, CO 80202
U.S. EPA Region 9 (includes: Arizona, California,
Hawaii, Nevada and Pacific Islands & Tribal Nations
subject to U.S. law)
Phone: (415)744-1500
75 Hawthorne
San Francisco, CA 94105
U.S. EPA Region 10 (includes: Alaska, Idaho, Oregon,
Washington)
Phone: (206) 553-1200
1200 6th Avenue
Seattle, WA 98101
State resources
Resource
56
Contact
Alabama
Water Supply Branch
Dept. of Environmental Management
Phone: (334) 271-7773
P.O. Box 301463
1400 Coliseum Blvd.
Montgomery, AL 36130-1463
Web Link: www.adem.state.al.us/EnviroProtect/Water/water.htm
Alaska
Drinking Water and Wastewater Program
Dept. of Environmental Conservation
Div. of Environmental Health
Phone: (907) 269-7500
555 Cordova St.
Anchorage, AK 99501
Web Link: www.state.ak.us/dec/deh/safewater.htm
American Samoa
American Samoa Environmental Protection Agency
Phone: (684) 633-2304
Office of the Governor
Pago Pago, AS 96799
Web Link: www.epa.gov/region09/cross_pr/islands/samoa.html
Arizona
Drinking Water Monitoring and Assessment Section
Water Quality Division
Dept. of Environmental Quality
Phone: (602) 207-4644
Room 200
3033 N. Central Ave.
Phoenix, AZ 85012-2809
Web Link: www.adeq.state.az.us/environ/water/dw/index.html
Arkansas
Div. of Engineering
Dept. of Health
Phone: (501) 661-2623
4815 W. Markham St. Mail Slot 37
Little Rock, AR 72205-3867
Web Link: www.healthyarkansas.com/eng/index.html
California Dept. of Health Services
Div. of Drinking Water and Environmental
Management
Phone: (916)323-6111
Web Link: www.dhs.cahwnet.gov/ps/ddwem/index.htm
Colorado
Drinking Water Program
Dept. of Public Health & Environment
WQCD-DW-B2
Phone: (303) 692-3500
4300 Cherry Creek Dr. S.
Denver, CO 80246-1530
Web Link: www.cdphe.state.co.us/wq/wqhom.asp
Connecticut
Water Supplies Section
Dept. of Public Health MS-51WAT
Phone: (860) 509-7333
P.O. Box 340308
Hartford, CT 06134-0308
Web Link: www.state.ct.us/dph/BRS/WSS/water_supplies.htm
Delaware
Div. of Public Health
Delaware Health & Social Services
Phone: (302) 739-5410
Blue Hen Corporate Center
655 Bay Rd.Dover, DE 19901
Web Link: www.state.de.us/dhss/dph/index.htm
Florida
Drinking Water Section
Dept. of Environmental Protection
Phone: (850) 487-1762
Twin Towers Office Building
2600 Blair Stone Rd.Tallahassee, FL 32399-2400
Web Link: www.dep.state.fl.us/water/default.htm
Georgia
Water Resources Branch
Environmental Protection Div.
Dept. of National Resources
Phone: (404) 656-5660
Floyd Towers E, Rm. 1362
205 Butler St., SE
Atlanta, GA 30334
Web Link: www.georgianet.org/dnr/environ
Resource
Contact
Guam
Guam Environmental Protection Agency
Phone: (671) 475-1658
Government of Guam
P.O. Box 22439 GMF
Barrigada, GU 96921
Web Link: www.admin.gov.gu/doa/GOVGUAMID/GEPA-ID_1.html
Hawaii
Environmental Management Div.
Hawaii Dept. of Health
Phone: (808) 586-4258
P.O. Box 3378
Honolulu, HI 96801
Web Link: www.hawaii.gov/health/eh/sdwb/
Idaho
Div. of Environmental Quality
Phone: (208) 373-0502
1410 N. Hilton
Boise, ID 83706
Web Link: www2.state.id.us/deq//water/water1.htm
Illinois
Div. of Public Water Supplies
Illinois Environmental Protection Agency
Phone: (217) 785-8653
P.O. Box 19276
Springfield, IL 62794-9276
Web Link: www.epa.state.il.us
Indiana
Drinking Water Branch
Office of Water Quality
Dept. of Environmental Management
Phone: (317) 308-3281
P.O. Box 6015
Indianapolis, IN 46206-6015
Web Link: www.state.in.us/idem/owm/dwb/index.html
Iowa
Water Quality Bureau
Iowa Dept. of Natural Resources
Phone: (515) 725-0275
401 SW 7th St., Suite "M"
900 E. Grant St.
Des Moines, IA 50309
Web Link:
www.state.ia.us/government/dnr/organiza/epd/wtrsuply/wtrsup.htm
Kansas
Public Water Supply Section
Bureau of Water
Kansas Dept. of Health & Environment
Phone: (785) 296-5514
1000 SW Jackson, Suite 420
Topeka, KS 66620
Web Link: www.kdhe.state.ks.us/water/pwss.html
Kentucky
Drinking Water Branch
Div. of Water
Dept. for Environmental Protection
Phone: (502) 564-3410
14 Reilly Rd.
Frankfort Office Park
Frankfort, KY 40601
Web Link: http://water.nr.state.ky.us/dw/
Louisiana
Div. of Environmental Health Services
Louisiana Dept. of Health & Hospitals
Office of Public Health
Phone: (225) 765-5038
6867 Blue Bonnet Blvd.
Baton Rouge, LA 70810
Web Link: www.dhh.state.la.us/OPH/safewtr.htm
Maine
Div. of Health Engineering
Maine Dept. of Human Services
Phone: (207) 287-2070
101 State House Station
Augusta, ME 04333
Web Link: http://janus.state.me.us/dhs/eng/water/index.htm
Maryland
Public Drinking Water Program
Dept. of the Environment
Phone: (410) 631-3702
Point Breeze Bldg. 40, Rm. 8L
2500 Broening Hwy.
Baltimore, MD 21224
Web Link: www.mde.state.md.us
Massachusetts
Phone: (617) 292-5770
One Winter St., 6th Floor
Boston, MA 02108
Web Link: www.state.ma.us/dep/brp/dws/dwshome.htm
Michigan
Drinking Water & Radiological Protection Div.Michigan
Phone: (517) 335-9218
Box 30630
Lansing, MI 48909-8130
Web Link: www.deq.state.mi.us/dwr
Minnesota
Drinking Water Protection Section
Dept. of Health
Phone: (651) 215-0770
121 E. Seventh Place
P.O. Box 64975
St. Paul, MN 55164-0975
Web Link: www.health.state.mn.us/divs/eh/eh.html
57
Resource
58
Contact
Mississippi
Div. of Water Supply
Dept. of Health
Phone: (601) 576-7518
P.O. Box 1700
2324 N. State Street
Jackson, MS 39215-1700
Web Link: www.msdh.state.ms.us/watersupply/index.htm
Missouri
Public Drinking Water Program
Dept. of Natural Resources
Phone: (573) 751-5331
P.O. Box 176
Jefferson City, MO 65101
Web Link: www.dnr.state.mo.us/deq/pdwp/homepdwp.htm
Montana
Phone: (406) 444-4323
Box 2000901
1520 E. Sixth Ave.
Helena, MT 59620-0901
Web Link: www.deq.state.mt.us/wqinfo/index.asp
Nebraska
Nebraska Dept. of HHS Regulation & Licensure
Phone: (402) 471-2541
301 Centennial Mall South
P.O. Box 95007, 3rd Floor
Lincoln, NE 68509-5007
Web Link: www.hhs.state.ne.us/
Nevada
Bureau of Health Protection Services
Dept. of Human Resources
Phone: (775) 687-4750
1179 Fairview Drive, Suite 101
Carson City, NV 89701-5405
Web Link: www.health2k.state.nv.us
New Hampshire
Water Supply Engineering Bureau
Dept. of Environmental Services
Phone: (603) 271-3139
P.O. Box 956 Hazen Drive
Concord, NH 03302-0095
Web Link: http://www.des.state.nh.us/wseb/
New Jersey
Bureau of Safe Drinking Water
Environmental Regulation
Phone: (609) 292-5550
P.O. Box CN-426
Trenton, NJ 08625
Web Link: www.state.nj.us/dep/watersupply/
New Mexico
Drinking Water Bureau
New Mexico Environment Dept.
Phone: (505) 827-7536 (877) 654-8720
525 Camino de los Marquez, Suite 4
Santa Fe, NM 87501
Web Link: www.nmenv.state.nm.us/dwb/dwbtop.html
New York
Bureau of Public Water Supply Protection
Dept. of Health
Phone: (518) 402-7650
547 River Street
Troy, NY 12180-7650
Web Link: www.health.state.ny.us/nysdoh/water/main.htm
North Carolina
Dept. of Env. and Natural Resources
Phone: (919) 733-2321
Box 29536
1634 Mail Service Center
Raleigh, NC 27699-1634
Web Link: www.deh.enr.state.nc.us/pws/index.htm
North Dakota
Div. of Municipal Facilities
North Dakota Dept. of Health
Phone: (701) 328-5211
1200 Missouri Avenue, Room 203
P.O. Box 5520
Bismark, ND 58506-5520
Web Link: www.ehs.health.state.nd.us/ndhd/environ/mf/index.htm
Northern Mariana Islands
Commonwealth of the Northern Mariana Islands
Phone: (670) 664-8500
P.O. Box 1304
Saipan, MP 96950
Web Link: NA
Ohio
Div. of Drinking & Ground Water
Ohio Environmental Protection Agency
Phone: (614) 644-2769
Lazarus Government Center
P.O. Box 1049
Columbus, OH 43216-1049
Web Link: www.epa.state.oh.us/ddagw/
Oklahoma
Water Quality Div.
Phone: (405) 271-4000
1000 Northeast 10th St.
Oklahoma City, OK 73101-1212
Web Link: www.deq.state.ok.us/water.html
Resource
Contact
Oregon
Dept. of Human Resources
Phone: (503) 731-4317
P.O. Box 14450
Portland, OR 97293-0450
Web Link: www.ohd.hr.state.or.us/dwp/welcome.htm
Pennsylvania
Bureau of Water Supply Management
Phone: (717) 787-9037
P.O. Box 8467
Harrisburg, PA 17105-8467
Web Link:
www.dep.state.pa.us/dep/deputate/watermgt/wmw/wmw.htm
Puerto Rico
Public Water Supply Supervision Program
Dept. of Health
Phone: (787) 754-6010
P.O. Box 70184
San Juan, PR 00936
Web Link: www.epa.gov/region02/cepd/compnum.htm#JCA
Rhode Island
Office of Drinking Water Quality
Dept. of Health
Phone: (401) 222-6867
3 Capitol Hill, Rm. 209
Providence, RI 02911
Web Link: www.health.state.ri.us/environment/dwq.htm
South Carolina
Bureau of Water
Dept. of Health & Environmental Control
Phone: (803) 734-5300
2600 Bull Street
Columbia, SC 29201
Web Link: www.scdhec.net/water/html/dwater.html
South Dakota
Div. of Environmental Regulation
Dept. of Environmental & Natural Resources
Phone: (605) 773-3754
523 East Capital Ave.
Joe Foss Building
Pierre, SD 57501
Web Link: www.state.sd.us/denr/des/drinking/dwprg.htm
Tennessee
Div. of Water Supply
Dept. of Environment & Conservation
Phone: (615) 532-0191
401 Church Street
L&C Tower, 6th Floor
Nashville, TN 37243
Web Link: www.state.tn.us/environment/dws/index.html
Texas
Water Utilities Div.
Texas Natural Resource Conservation Commission
Phone: (512) 239-6096
P.O. Box 13087
Austin, TX 78711
Web Link:
www.tnrcc.state.tx.us/permitting/waterperm/pdw000.html
Utah
Div. of Drinking Water
Phone: (801) 536-4200
P.O. Box 144830
Salt Lake City, UT 84118
Web Link: www.deq.state.ut.us/eqdw/
Vermont
Water Supply Div.
Dept. of Environmental Conservation
Phone: (802) 241-3400
Old Pantry Bldg
103 South Main Street
Waterbury, VT 05671
Web Link: www.anr.state.vt.us/dec/watersup/wsd.htm
Virgin Islands
Div. of Environmental Protection
Dept. of Planning & Natural Resources
Phone: (340) 774-3320
Wheatley Center 2
St. Thomas, VI 00802
Web Link: NA
Virginia
Div. of Water Supply Engineering
Dept. of Health
Phone: (804) 786-5566
Room 109-31
1500 East Main Street
Richmond, VA 23219
Web Link: www.vdh.state.va.us/owp/water_supply.htm
Washington
Drinking Water Div.
Dept. of Health
Phone: (360) 236-3100 (800) 521-0323
Washington Industrial Center, Building 3
P.O. Box 47822
Olympia, WA 98504
Web Link: http://www.doh.wa.gov/ehp/dw/
Washington, DC
Environmental Health Administration
Phone: (202) 535-2500
51 N Street, NE
Web Link: www.dchealth.com/eha/welcome.htm
59
Resource
Contact
West Virginia
Environmental Engineering Div.
Office of Environmental Health Services
Bureau for Public Health
Phone: (304) 558-2981
815 Quarrier Street, Suite 401
Charleston, WV 25301
Web Link: www.wvdhhr.org/bph/enviro.htm
Wisconsin
Drinking Water & Groundwater
Wisconsin Dept. of Natural Resources
Phone: (608) 266-2299
P.O. Box 7921
Madison, WI 53703
Web Link: www.dnr.state.wi.us/org/water/dwg/
Wyoming
Wyoming Drinking Water Program
EPA Region VIII
Phone: (307) 777-7781
122 W. 25th Street
Herschler Building
Cheyenne, WY 82002
Web Link: http://deq.state.wy.us/wqd.htm
Other resources
Resource
60
Contact
American Public Works Association
Phone: (816) 472-6100
2345 Grand Blvd., Suite 500
Kansas City, MO 64108-2641
Web Link: www.apwa.net
Phone: (303) 794-7711
6666 W. Quincy Avenue
Denver, CO 80235
Web Link: www.awwa.org
Small Utility Network
Phone: (800) 366-0107
Web Link: www.awwa.org/sun/sunhome.htm
Association of State Drinking Water Administrators
Phone: (202) 293-7655
1025 Connecticut Ave., NW Suite 903
Washington, D.C., 20036
Web Link: www.asdwa.org
National Drinking Water Clearinghouse
National Environmental Services Center
Phone: (800) 624-8301 (304) 293-4191
West Virginia University
P.O. Box 6064
Morgantown, WV 26506
Web Link: www.ndwc.wvu.edu AND www.nesc.wvu.edu
National Rural Water Association
Phone: (580) 252-0629
2915 South 13th Street
Duncan, OK 73533-9086
Web Link: www.nrwa.org
National Small Flows Clearinghouse
Web Link: www.nesc.wvu.edu
NSF International
Phone: (734) 769-8010, (800) NSF-MARK
PO Box 130140
789 N. Dixboro Road
Ann Arbor, MI 48113-0140
Web Link: http://www.nsf.org/water.html
Rural Community Assistance Corporation
Phone: (916) 376-0507
3120 Freeboard Dr. Suite 201
West Sacramento, CA 95691
Web Link: http://www.rcac.org/
Rural Community Assistance Program
Phone: (202) 408-1273
1522 K Street, NW, Suite 400
Web Link: www.rcap.org
Safe Drinking Water Foundation
Phone: (306) 934-0389
11 Innovation Blvd.
Saskatoon, SK Canada, S7N 3H5
Web Link: www.safewater.org
Resource
Contact
Universities Water Information Network
Phone: (618) 453-6026
UWIN 4436, Faner Hall
Southern Illinois University
Carbondale, IL 62901
Web Link: www.uwin.siu.edu/index.html
Water Quality Association
Phone: (630) 505-0160
4151 Naperville Road;
isle, IL 60532
Web Link: http://www.wqa.org/
61
62
12.0 References
1. Virginia Water Resources Research Center,
(1996), A Guide to the National Drinking Water
Standards and Private Water Systems,
Blacksburg, Virginia.
12. Craun, G., Goodrich, J. A., Lykins, B. W.,
Schwartz, E., “How to Select a Personal and
Household Drinking Water Treatment System: A
Guide to Peace Corps Personnel,” June 2, 1997.
2. U.S. Environmental Protection Agency (1999),
25 Years of the Safe Drinking Water Act: History
and Trends.
13. U.S. Environmental Protection Agency (April
2001), Low-Pressure Membrane Filtration For
Pathogen Removal: Application,
Implementation, and Regulatory Issues (EPA815-C-01-001).
3. Geldreich, E. E., et al., “The Necessity of
Controlling Bacterial Populations in Potable
Waters - Bottled Water and Emergency Water
Supplies,” Journal American Water Works
Association, Vol. 67, No.3, March 1975.
4. Prince, R., “Water Purification: a basic
overview,” Pacific Mountain Network News,
Rural Community Assistance Corporation, West
Sacramento, CA. Vol. XIX, Number 4, July, 2001.
5. U.S. Environmental Protection Agency
(September 1998), Variance Technology Findings
for Contaminants Regulated Before 1996 (EPA
815-R-98-003)
6. Goodrich, J. A., “Innovative Technologies for
Small Drinking Water Systems,” presented at the
Japan - U.S. Governmental Conference on
Drinking Water Quality Management and
Wastewater Control, Colorado Springs, CO., July
24–30, 1999.
7.
MacDonald, J. A., Zander, A. K., and Snoeyink,
V. L., “Improving service to small communities.”
Journal American Water Works Association,
89(1): 58-64, 1997.
8. U.S. Environmental Protection Agency (July
1999), Small System Regulatory Requirements
Under the Safe Drinking Water Act as Amended,
(EPA-R-99-011).
9. Pollack, A. J., Chen, A. S. C., Haught, R. C.,
Goodrich, J. A.; (1999), Options for Remote
Monitoring and Control of Small Drinking Water
Facilities, Battelle Press, Columbus, Ohio.
(September 1998), Small System Compliance
Technology List for the Non-Microbial
Contaminants Regulated Before 1996 (EPA-815R-98-002).
(September 1998), Small System Compliance
Technology List for the Surface Water Treatment
Rule and Total Coliform Rule (EPA-815-R-98001).
14. Goodrich, J. A., Lykins, B. W., Haught, R. C. and
Li, S. Y., “Bag Filtration for Small Systems,” in
Providing Safe Drinking Water in Small Systems,
Edited by Joseph A. Cotruvo, Gunther F. Craun
and Nancy Hearne, Pan American Health
Organizations, World Health Organizations, ILSI
Press, Washington, DC, 1999, pp 265-272.
15. Goodrich, J.A., Haught, R.C., (2000) Controlling
Disinfection By-Products and Microbial
Contaminants in Small Public Water Systems,
GPRA Report, U.S. Environmental Protection
Agency, Office of Research and Development,
National Risk Management Research
Laboratory.
16. Jacangelo, J. G., Adham, S., and Laine, J. M.,
Membrane Filtration for Microbial Removal,
AWWARF, Denver, CO, 1997.
17. Li, S. Y., Cryptosporidium potential surrogate
and compressibility investigations for evaluating
filtration-based water treatment technologies.
Master’s thesis, Miami University, Oxford, Ohio,
November 1994.
40 CFR Parts 141 and 142; Drinking Water;
National Primary Drinking Water Regulations;
Filtration, Disinfection; Turbidity, Giardia
lamblia, Viruses, Legionella, and Heterotrophic
Bacteria; Final Rule, Federal Register, 54(124),
27486-27541, June 19, 1989.
19. Lykins, B.W., Goodrich, J.A., and Hoff, J.C.,
“Concerns with using Chlorine-dioxide
Disinfection in the USA.” Journal of Water
Supply Research Technology 39(6): 376-386,
1990.
40 CFR Parts 141, and 142; National Primary
Drinking Water Regulations; Enhanced Surface
Water Treatment Requirements; Proposed Rule,
Federal Register, 59(145), 38832-38858, July 29,
1994.
63
21. Clark, R. M., Goodrich, J. A., and Lykins Jr., B.
W., “Package Plants for Small Water Supplies B
The U.S. Experience.” Journal of Water Supply
Research Technology 43(1): 23-34, 1994.
22. Gordon, G., Gauw, R., Walters, B., Goodrich, J.
A., Krishnan, R. A., and Bubnis, B., “Chemical
Detail of Electrolyzed Salt Brine Solutions,”
presented at the AWWA National Conference
and Exposition, Chicago, ILL, June, 1999.
23. Standard Methods for the Examination of Water
and Wastewater, 20th Edition, Published by
APHA, AWWA and WPCF, 1998.
24. Vel Leitner, N.K., Papailhou, A.L., Croue, J.P.,
Peyrot, J., and Dore, M., “Oxidation of Methyl tButyl Ether (MTBE) and Ethyl t-Butyl Ether
(ETBE) by Ozone and Combined Ozone/
Hydrogen Peroxide.” Ozone Science and
Engineering, Vol. 16, pp 41-44. 1994.
25. Liang, S., et. al., “Oxidantion of MTBE by
Ozone and Peroxone Processes.” AWWA, Vol 91,
Issue 6, pp 104-114, June 1999.
26. Lykins, B. W., Clark, R. M., Goodrich, J. A.;
(1992), Point-of-Use/Point-of-Entry for Drinking
Water Treatment, Lewis Publishers, Ann Arbor,
MI.
27. Goodrich, J.A., Adams, J.O., Lykins, B.W., and
Clark, R.M., Safe Drinking Water from Small
Systems and Treatment Options.” Journal
American Water Works Association, 84(5): 4955, 1992
28. Lykins, B.W., Astle, R., Schlafer, J.L., and
Shanaghan, P.E., “Reducing Fluoride by
Managed POU Treatment”, Journal American
Water Works Association, November, 1995, pp
57-65.
29. Lykins, B. W., Goodrich, J.A., Clark, R.M., and
Harrison, J., “Point-of-Use/Point-of-Entry
Treatment of Drinking Water,” Presented at
International Water Supply Association
Congress, Budapest, Hungary, October 1993.
30. Goodrich, J. A., Lykins, Jr., B. W., and Gordon,
P., “Ozone Point-Of-Entry Field Applications,”
presented at the 11th Ozone World Congress, San
Francisco, CA, September 1, 1993.
31. Haught, R. C., “The Use of Remote Telemetry to
Complement the Operations and Maintenance of
a Small Treatment System.” In Proceedings of
the 1998 AWWA Annual Conference, Dallas, TX,
1998.
64
32. Haught, R. C., and Panguluri, S., “Innovations
for Management of Remote Telemetry Systems
for Small Drinking Water Treatment Plants.”
Paper presented at the First International
Symposium on Safe Drinking Water in Small
Systems, Washington, DC, May 10–13, 1998.
33. National Drinking Water Clearinghouse (Spring
2001), On Tap – Distribution Systems,
Morgantown, WV.
34. Campbell, S., Lykins, B. W., Goodrich, J. A.,
“Financing Assistance Available for Small
Public Water Systems.” (EPA/600/J-93/270).
ACKNOWLEDGEMENTS
The contributors and reviewers include James Goodrich
(EPA), Roy Haught (EPA), Eric Bissonette (EPA), Chuck
Guion (EPA), Srinivas Panguluri (IT), Rajib Sinha (IT),
Sylvana Li (formerly with IT) and Harriet Emerson (NESC).
The authors would also like to thank everyone involved in
conducting the research at the EPA Test & Evaluation Fa
cility and at other field locations.

Small Drinking Water Systems Handbook

Transcription

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